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  • 1.
    Albertsson, Marcus
    et al.
    Linköping University, Department of Computer and Information Science.
    Öberg Bustad, Adrian
    Linköping University, Department of Computer and Information Science.
    Sundmark, Mattias
    Linköping University, Department of Computer and Information Science.
    Gerde, Elof
    Linköping University, Department of Computer and Information Science.
    Boberg, Jessika
    Linköping University, Department of Computer and Information Science.
    Abdulla, Ariyan
    Linköping University, Department of Computer and Information Science.
    Danielsson, Oscar
    Linköping University, Department of Computer and Information Science.
    Johnsson Bittmann, Felicia
    Linköping University, Department of Computer and Information Science.
    Moberg, Anton
    Linköping University, Department of Computer and Information Science.
    Hur en webbapplikation kan utvecklas för att leverera säkerhet, handlingsbarhet och navigerbarhet: PimpaOvven – Utveckling av en e-butik för märken och accessoarer till studentoveraller2017Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    Among students in many of Sweden’s Universities the student overall is an established possession. Many students like to decorate their overalls with embroidered patches and other types of accessories, the supply of these is however limited. This report presents the development process and result of the web application “PimpaOvven” – an e-shop with the purpose of increasing the accessibility of patches and overall accessories. The development has been iterative and focused on building a secure web application that generates a useable environment regarding actability and navigability that also provides an impression of security to the user. The methods used which generated the resulting web application together with the reference framework form the basis of the report’s discussion. During the project plenty of usability tests and security tests were conducted, from these tests together with the report’s discussion the conclusion was drawn that the produced web application was secure and useable.

  • 2.
    Andersson, Peter
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Informationsteknologi i organisationer: bestämningsfaktorer och mönster1989Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Researchers in this field have placed different emphasis on the structural constraints visa- vis the freedom of the actors. An awareness that IT is a social construction does not necessarily mean that some individual actor or actor entity can perform freely. An inflexible, tightly structured social situation can considerably limit the action space. Actors are hemmed in by "objective" circumstances, ie, a rather closely controlled situation established by other actors, and which is apparently unyielding in the face of technological decisions.

    By creating a perspective that addresses both structural and actor aspects, this study attempts a holistic understanding which will lay bare the probable dialectic process between the changeable and the nonchangeable. This aspiration to comprehend the whole, when viewed against the complex character of the subject, calls for an understanding oriented approach.

    The study at hand deals with the choice of information technology in organizations, with special focus on automatic data processing (ADP) for administrative purposes. Its main aim is to improve an understanding of factors that determine the choice of ADP technology in organizations.

    The empirical section of the work at hand consists of two case studies and an overview study. The case studies, which concern two extensive ADP projects, are emphasized. The purpose of these two projects was to raise the degree of computerization and to choose both a configuration and degree of uniformity. In both cases however the configuration turned out to be the most critical issue. One concerned the administration of social insurance in Sweden, Rationalisering av den allmänna försäkringens administration (Rationalization of the Swedish social insurance administration), hereafter called the RAFA project. The other case study, referred to here as the FFV study, deals with an administrative system for the manufacturing sector of the FFV Group  The overview study, called the Norrköping study, deals mainly with the technological level and the ADP configuration in a wide spectrum of organizations. The level and the configuration are viewed against an overarching organizational structure, the worksite placement of qualified ADP staff, the line of business and the size of the firm. The study consists of an opinion poll and three delimited secondary studies.

    In the initial stage of each project, rational motives dominated. These were founded on cost and effect assessments and on developments in the field of computer science. From a structural viewpoint, investments in computers seemed self-evident; efficiency goals were paramount. However, an ADP undertaking entails not only rationalization in the conventional sense, it also brings to the ideational aspects inherent in the organization. While ADP technology was believed necessary, it became, in the preplanning and argumentation phase, a means of projecting socially determined concepts and goals. An ADP solution was sought which would combine the latest innovations in computer science with the dominant actors' organizational ideas.

    The dominant actors at FFV were for the most part newly appointed managers, imprinted with other organizational ideals and relationships than those characterizing FFV. The choice stood between a departure from company tradition by selecting a solution based on local minicomputers, or expanding the existing centralized main frame facility. The critics were specialists who had taken part in the design of the existing configuration. At FFV, the structural determinants had to be toned down in favor of the deliberate performance of the dominant actors. In the RAF A case, the opposite was true. The critics wanted a certain change of existing circumstances, while the dominant actors sought to preserve status quo and its underlying ideas. In the RAF A case, ADP thus became a cementing force rather than the catalyst.

    The Norrkoping study clearly indicates that the direction and size of an enterprise has primary importance for how much the computers are used. The ADP configuration appearance varies mainly with the organizational relationships. This is true for the placement of ADP staff and the overall structure of the organization. The main tendency is that the configuration reflects the relationships in an organization. This supports the view in the case studies that proximity to and control of the ADP has a major organizational value.

  • 3.
    Andersson, Tim
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Bluetooth Low Energy and Smartphones for Proximity-Based Automatic Door Locks2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Bluetooth Low Energy is becoming increasingly popular in mobile applications due to the possibility of using it for proximity data. Proximity can be estimated by measuring the strength of the Bluetooth signal, and actions can then be performed based on a user's proximity to a certain location or object. One of the most interesting applications of proximity information is automating common tasks; this paper evaluates Bluetooth Low Energy in the context of using smartphones to automatically unlock a door when a user approaches the door. Measurements were performed to determine signal strength reliability, energy consumption and connection latency. The results show that Bluetooth Low Energy is a suitable technology for proximity-based door locks despite the large variance in signal strength.

  • 4.
    Arding, Petter
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hedelin, Hugo
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Computer virus: design and detection2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Computer viruses uses a few different techniques, with various intentions, toinfect files. However, what most of them have in common is that they wantto avoid detection by anti-malware software. To not get detected and stay unnoticed,virus creators have developed several methods for this. Anti-malwaresoftware is constantly trying to counter these methods of virus infections withtheir own detection-techniques. In this paper we have analyzed the differenttypes of viruses and their infection techniques, and tried to determined whichworks the best to avoid detection. In the experiments we have done we havesimulated executing the viruses at the same time as an anti-malware softwarewas running. Our conclusion is that metamorphic viruses uses the best methodsto stay unnoticed by anti-malware software’s detection techniques.

  • 5.
    Arvidsson, Martin
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Paulsson, Eric
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Utveckling av beslutsstöd för kreditvärdighet2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim is to develop a new decision-making model for credit-loans. The model will be specific for credit applicants of the OKQ8 bank, becauseit is based on data of earlier applicants of credit from the client (the bank). The final model is, in effect, functional enough to use informationabout a new applicant as input, and predict the outcome to either the good risk group or the bad risk group based on the applicant’s properties.The prediction may then lay the foundation for the decision to grant or deny credit loan.

    Because of the skewed distribution in the response variable, different sampling techniques are evaluated. These include oversampling with SMOTE, random undersampling and pure oversampling in the form of scalar weighting of the minority class. It is shown that the predictivequality of a classifier is affected by the distribution of the response, and that the oversampled information is not too redundant.

    Three classification techniques are evaluated. Our results suggest that a multi-layer neural network with 18 neurons in a hidden layer, equippedwith an ensemble technique called boosting, gives the best predictive power. The most successful model is based on a feed forward structure andtrained with a variant of back-propagation using conjugate-gradient optimization.

    Two other models with a good prediction quality are developed using logistic regression and a decision tree classifier, but they do not reach thelevel of the network. However, the results of these models are used to answer the question regarding which customer properties are importantwhen determining credit risk. Two examples of important customer properties are income and the number of earlier credit reports of the applicant.

    Finally, we use the best classification model to predict the outcome of a set of applicants declined by the existent filter. The results show that thenetwork model accepts over 60 % of the applicants who had previously been denied credit. This may indicate that the client’s suspicionsregarding that the existing model is too restrictive, in fact are true.

  • 6.
    Axetun, Magnus
    Linköping University, Department of Computer and Information Science.
    Securing hospitals from exploitation of hardware ports2017Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Electronic devices are widely used in today’s hospitals and the possibilities they offer are increasing every day. The devices are often embedded systems, running outdated operating systems and need to have a high uptime which makes them vulnerable to malicious software (malware). This thesis examines the ways malware can propagate through the Universal Serial Bus (USB) with the help of social engineering. Valuable assets are defined and different threat scenarios to these assets are presented. Lastly, the different scenarios are evaluated based on which assets they impact and how to effective mitigate the threats they present. Short- and long-term mitigations are presented to secure the devices in a broader view.

  • 7. Banissi, Ebad
    et al.
    Bertschi, StefanBurkhard, RemoCvek, UrskaEppler, MartinForsell, CamillaLinköping University, Department of Science and Technology, Media and Information Technology.Grinstein, GeorgesJohansson, JimmyLinköping University, Department of Science and Technology, Media and Information Technology.Kenderdine, SarahMarchese, Francis T.Maple, CarstenTrutschl, MarjamSarfraz, MuhammadStuart, LizUrsyn, AnnaWyeld, Theodor G.
    Information Visualization2011Conference proceedings (editor) (Refereed)
  • 8.
    Belka, Kamila
    Linköping University, Department of Computer and Information Science.
    Multicriteria analysis and GIS application in the selection of sustainable motorway corridor2005Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Effects of functioning transportation infrastructure are receiving more and more environmental and social concern nowadays. Nevertheless, preliminary corridor plans are usually developed on the basis of technical and economic criteria exclusively. By the time of environmental impact assessment (EIA), which succeeds, relocation is practically impossible and only preventative measures can be applied.

    This paper proposes a GIS-based method of delimiting motorway corridor and integrating social, environmental and economic factors into the early stages of planning. Multiple criteria decision making (MCDM) techniques are used to assess all possible alternatives. GIS-held weighted shortest path algorithm enables to locate the corridor. The evaluation criteria are exemplary. They include nature conservation, buildings, forests and agricultural resources, and soils. Resulting evaluation surface is divided into a grid of cells, which are assigned suitability scores derived from all evaluation criteria. Subsequently, a set of adjacent cells connecting two pre-specified points is traced by the least-cost path algorithm. The best alternative has a lowest total value of suitability scores.

    As a result, the proposed motorway corridor is routed from origin to destination. It is afterwards compared with an alternative derived by traditional planning procedures. Concluding remarks are that the location criteria need to be adjusted to meet construction

    requirements as well as analysis process to be automated. Nevertheless, the geographic information system and the embedded shortest path algorithm proved to be well suited for preliminary corridor location analysis. Future research directions are sketched.

  • 9.
    Bergdahl, Filip
    Linköping University, Department of Science and Technology.
    Analys av lämplighet för användning av RFID-teknik inom Schenkers verksamhet2007Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [sv]

    Radio Frequency Identification är en relativt gammal teknik (sedan andra världskriget), som upplevt en renässans. Då som nu användes RFID för att identifiera föremål, dock med vissa tekniska skillnader. Ökade krav på industrier och samhället i övrigt har lett till den ”informa-tionsålder” vi nu lever i. Som ett steg i denna utveckling ställs allt högre krav på insamlingen av den information som många processer och beslut baseras på. Förenklat kan kommunika-tionen förklaras som en radiosignal som skickas från en RFID-läsare till en RFID-tagg. Taggen sitter på objektet som skall identifieras och information om objektet finns lagrad i taggen. Radiosignalen väcker taggen som skickar den information som finns lagrad i dess mikrochip tillbaka till läsaren. RFID kan användas i en stor mängd olika områden och applikationer där två av dessa är inom transportnätverk och försörjningskedjor. Anledningen till att detta projekt initierades var att logistikföretaget Schenker AB såg ett behov i att undersöka hur tekniken kan användas inom deras verksamhet. För Schenkers del var det viktigt att få utreda eventuella möjligheter med tekniken, och dess kostnader innan kunderna kom med krav eller önskemål om användning. Tre förslag på hur RFID kan användas i verksamheten har utarbetats för att få en bra bild av hur användningen kan gå till och vad som krävs. Studien visar att det krävs en hel del av Schenker i form av utrustning och även datasystem. De slutsatser som kan dras efter att projektet är genomfört är att det finns potential för förbättringar vid användning av RFID-teknik inom Schenkers verksamhet. Dock är dessa förknippade med relativt höga initiala kostnader. Vidare finns även en del tekniska begränsningar vilket gör att systemet måste planeras och konstrueras noggrant för full funktionalitet. Ytterligare undersökningar måste göras för att få mer underlag för hur pass väl RFID kan användas inom Schenker. Tester och försök i mindre flöden hos Schenker vore ett bra sätt för att få erfarenhet och kunskap om teknikens funktionalitet, möjligheter och begränsningar.

  • 10.
    Berggren, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Simon, Daniel
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nilsson, D
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Dyreklev, P
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Norberg, P
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Nordlinder, S
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Ersman, PA
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Gustafsson, G
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Wikner, Jacob
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    Hederén, J
    DU Radio, Ericsson AB, SE-583 30, Linköping, Sweden..
    Hentzell, H
    Swedish ICT Research, Box 1151, SE-164 26, Kista, Sweden..
    Browsing the Real World using Organic Electronics, Si-Chips, and a Human Touch.2016In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 10, 1911-1916 p.Article in journal (Refereed)
    Abstract [en]

    Organic electronics have been developed according to an orthodox doctrine advocating "all-printed, "all-organic and "ultra-low-cost primarily targeting various e-paper applications. In order to harvest from the great opportunities afforded with organic electronics potentially operating as communication and sensor outposts within existing and future complex communication infrastructures, high-quality computing and communication protocols must be integrated with the organic electronics. Here, we debate and scrutinize the twinning of the signal-processing capability of traditional integrated silicon chips with organic electronics and sensors, and to use our body as a natural local network with our bare hand as the browser of the physical world. The resulting platform provides a body network, i.e., a personalized web, composed of e-label sensors, bioelectronics, and mobile devices that together make it possible to monitor and record both our ambience and health-status parameters, supported by the ubiquitous mobile network and the resources of the "cloud".

  • 11.
    Bivall, Petter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Touching the Essence of Life: Haptic Virtual Proteins for Learning2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation presents research in the development and use of a multi-modal visual and haptic virtual model in higher education. The model, named Chemical Force Feedback (CFF), represents molecular recognition through the example of protein-ligand docking, and enables students to simultaneously see and feel representations of the protein and ligand molecules and their force interactions. The research efforts have been divided between educational research aspects and development of haptic feedback techniques.

    The CFF model was evaluated in situ through multiple data-collections in a university course on molecular interactions. To isolate possible influences of haptics on learning, half of the students ran CFF with haptics, and the others used the equipment with force feedback disabled. Pre- and post-tests showed a significant learning gain for all students. A particular influence of haptics was found on students reasoning, discovered through an open-ended written probe where students' responses contained elaborate descriptions of the molecular recognition process.

    Students' interactions with the system were analyzed using customized information visualization tools. Analysis revealed differences between the groups, for example, in their use of visual representations on offer, and in how they moved the ligand molecule. Differences in representational and interactive behaviours showed relationships with aspects of the learning outcomes.

    The CFF model was improved in an iterative evaluation and development process. A focus was placed on force model design, where one significant challenge was in conveying information from data with large force differences, ranging from very weak interactions to extreme forces generated when atoms collide. Therefore, a History Dependent Transfer Function (HDTF) was designed which adapts the translation of forces derived from the data to output forces according to the properties of the recently derived forces. Evaluation revealed that the HDTF improves the ability to haptically detect features in volumetric data with large force ranges.

    To further enable force models with high fidelity, an investigation was conducted to determine the perceptual Just Noticeable Difference (JND) in force for detection of interfaces between features in volumetric data. Results showed that JNDs vary depending on the magnitude of the forces in the volume and depending on where in the workspace the data is presented.

    List of papers
    1. Designing and Evaluating a Haptic System for Biomolecular Education
    Open this publication in new window or tab >>Designing and Evaluating a Haptic System for Biomolecular Education
    Show others...
    2007 (English)In: IEEE Virtual Reality Conference, 2007. VR '07. / [ed] Sherman, W; Lin, M; Steed, A, Piscataway, NJ, USA: IEEE , 2007, 171-178 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    In this paper we present an in situ evaluation of a haptic system, with a representative test population, we aim to determine what, if any, benefit haptics can have in a biomolecular education context. We have developed a haptic application for conveying concepts of molecular interactions, specifically in protein-ligand docking. Utilizing a semi-immersive environment with stereo graphics, users are able to manipulate the ligand and feel its interactions in the docking process. The evaluation used cognitive knowledge tests and interviews focused on learning gains. Compared with using time efficiency as the single quality measure this gives a better indication of a system's applicability in an educational environment. Surveys were used to gather opinions and suggestions for improvements. Students do gain from using the application in the learning process but the learning appears to be independent of the addition of haptic feedback. However the addition of force feedback did decrease time requirements and improved the students understanding of the docking process in terms of the forces involved, as is apparent from the students' descriptions of the experience. The students also indicated a number of features which could be improved in future development.

    Place, publisher, year, edition, pages
    Piscataway, NJ, USA: IEEE, 2007
    Keyword
    Haptic Interaction, Haptics, Virtual Reality, Computer-assisted instruction, Life Science Education, Protein Interactions, Visualization, Protein-ligand docking
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-39934 (URN)10.1109/VR.2007.352478 (DOI)000245919300022 ()51733 (Local ID)1-4244-0906-3 (ISBN)51733 (Archive number)51733 (OAI)
    Conference
    IEEE Virtual Reality Conference, Charlotte, NC, USA, 10-14 March 2007
    Note

    ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Petter Bivall Persson, Matthew Cooper, Lena Tibell, Shaaron Ainsworth, Anders Ynnerman and Bengt-Harald Jonsson, Designing and Evaluating a Haptic System for Biomolecular Education, 2007, IEEE Virtual Reality Conference 2007, 171-178. http://dx.doi.org/10.1109/VR.2007.352478

    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2016-05-04Bibliographically approved
    2. Improved Feature Detection over Large Force Ranges Using History Dependent Transfer Functions
    Open this publication in new window or tab >>Improved Feature Detection over Large Force Ranges Using History Dependent Transfer Functions
    Show others...
    2009 (English)In: Third Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, WorldHaptics 2009, IEEE , 2009, 476-481 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    In this paper we present a history dependent transfer function (HDTF) as a possible approach to enable improved haptic feature detection in high dynamic range (HDR) volume data. The HDTF is a multi-dimensional transfer function that uses the recent force history as a selection criterion to switch between transfer functions, thereby adapting to the explored force range. The HDTF has been evaluated using artificial test data and in a realistic application example, with the HDTF applied to haptic protein-ligand docking. Biochemistry experts performed docking tests, and expressed that the HDTF delivers the expected feedback across a large force magnitude range, conveying both weak attractive and strong repulsive protein-ligand interaction forces. Feature detection tests have been performed with positive results, indicating that the HDTF improves the ability of feature detection in HDR volume data as compared to a static transfer function covering the same range.

    Place, publisher, year, edition, pages
    IEEE, 2009
    Keyword
    Haptics, Virtual Reality, Scientific Visualization
    National Category
    Interaction Technologies
    Identifiers
    urn:nbn:se:liu:diva-45355 (URN)10.1109/WHC.2009.4810843 (DOI)81912 (Local ID)978-1-4244-3858-7 (ISBN)81912 (Archive number)81912 (OAI)
    Conference
    Third Joint EuroHaptics conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems. World Haptics 2009.Salt Lake City, UT, USA, 18-20 March 2009
    Projects
    VisMolLS
    Note

    ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Petter Bivall Persson, Gunnar E. Höst, Matthew D. Cooper, Lena A. E. Tibell and Anders Ynnerman, Improved Feature Detection over Large Force Ranges Using History Dependent Transfer Functions, 2009, Third Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, WorldHaptics 2009, 476-481. http://dx.doi.org/10.1109/WHC.2009.4810843

    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2016-05-04Bibliographically approved
    3. Do Haptic Representations Help Complex Molecular Learning?
    Open this publication in new window or tab >>Do Haptic Representations Help Complex Molecular Learning?
    2011 (English)In: Science Education, ISSN 0036-8326, E-ISSN 1098-237X, Vol. 95, no 4, 700-719 p.Article in journal (Refereed) Published
    Abstract [en]

    This study explored whether adding a haptic interface (that provides users with somatosensory information about virtual objects by force and tactile feedback) to a three-dimensional (3D) chemical model enhanced students' understanding of complex molecular interactions. Two modes of the model were compared in a between-groups pre- and posttest design. In both modes, users could move and rotate virtual 3D representations of the chemical structures of the two molecules, a protein and a small ligand molecule. In addition, in a haptic mode users could feel the interactions (repulsive and attractive) between molecules as forces with a haptic device. Twenty postgraduate students (10 in each condition) took pretests about the process of protein--ligand recognition before exploring the model in ways suggested by structured worksheets and then completing a posttest. Analysis addressed quantitative learning outcomes and more qualitatively students' reasoning during the learning phase. Results showed that the haptic system helped students learn more about the process of protein–ligand recognition and changed the way they reasoned about molecules to include more force-based explanations. It may also have protected students from drawing erroneous conclusions about the process of protein–ligand recognition observed when students interacted with only the visual model.

    Keyword
    Haptic learning, multimodality, molecular interactions, protein-ligand docking
    National Category
    Didactics Biochemistry and Molecular Biology Media and Communication Technology
    Identifiers
    urn:nbn:se:liu:diva-60354 (URN)10.1002/sce.20439 (DOI)
    Projects
    VisMolLS
    Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2018-01-12
    4. Using logging data to visualize and explore students’ interaction and learning with a haptic virtual model of protein-ligand docking
    Open this publication in new window or tab >>Using logging data to visualize and explore students’ interaction and learning with a haptic virtual model of protein-ligand docking
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This study explores students’ interaction and learning with a haptic virtual model of biomolecular recognition. Twenty students assigned to a haptics or no-haptics condition performed a protein-ligand docking task where interaction was captured in log files. Any improvement in understanding of recognition was measured by comparing written responses to a conceptual question before and after interaction. A log-profiling tool visualized students’ traversal of the ligand while multivariate parallel coordinate analyses uncovered trends in the data. Students who experienced force feedback (haptics) displayed docked positions that were more clustered in comparison with no-haptics students, coupled to docking profiles that depicted a more focused traversal of the ligand. Students in the no-haptics condition employed double the amount of behaviours concerned with switching between multiple visual representations offered by the system. In the no-haptics group, this visually intense processing was associated with ‘fitting’ the ligand closer distances to the surface of the protein. A negative relationship between high representational switching activity and learning gain as well as spatial aptitude was also revealed. From an information-processing perspective, visual and haptic coordination could permit engagement of each perceptual channel simultaneously, in effect offloading the visual pathway by placing less strain on visual working memory.

    Keyword
    Interactive learning environments; multimedia systems; pedagogical issues; postsecondary education; virtual reality
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-60355 (URN)
    Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2016-05-04
    5. Haptic Just Noticeable Difference in Continuous Probing of Volume Data
    Open this publication in new window or tab >>Haptic Just Noticeable Difference in Continuous Probing of Volume Data
    2010 (English)Report (Other academic)
    Abstract [en]

    Just noticeable difference (JND) describes how much two perceptual sensory inputs must differ in order to be distinguishable from each other. Knowledge of the JND is vital when two features in a dataset are to be separably represented. JND has received a lot of attention in haptic research and this study makes a contribution to the field by determining JNDs during users' probing of volumetric data at two force levels. We also investigated whether these JNDs were affected by where in the haptic workspace the probing occurred. Reference force magnitudes were 0.1 N and 0.8 N, and the volume data was presented in rectangular blocks positioned at the eight corners of a cube 10 cm3 in size. Results showed that the JNDs varied significantly for the two force levels, with mean values of 38.5% and 8.8% obtained for the 0.1 N and 0.8 N levels, respectively, and that the JND was influenced by where the data was positioned.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2010. 19 p.
    Series
    Technical reports in Computer and Information Science, ISSN 1654-7233 ; 6
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-58011 (URN)
    Available from: 2010-07-16 Created: 2010-07-16 Last updated: 2010-10-12Bibliographically approved
  • 12.
    Bladin, Kalle
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Axelsson, Emil
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Broberg, Erik
    Linköping University, Faculty of Science & Engineering.
    Emmart, Carter
    Amer Museum Nat Hist, NY 10024 USA.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Bock, Alexander
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering. NYU, NY 10003 USA.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Globe Browsing: Contextualized Spatio-Temporal Planetary Surface Visualization2018In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 24, no 1, 802-811 p.Article in journal (Refereed)
    Abstract [en]

    Results of planetary mapping are often shared openly for use in scientific research and mission planning. In its raw format, however, the data is not accessible to non-experts due to the difficulty in grasping the context and the intricate acquisition process. We present work on tailoring and integration of multiple data processing and visualization methods to interactively contextualize geospatial surface data of celestial bodies for use in science communication. As our approach handles dynamic data sources, streamed from online repositories, we are significantly shortening the time between discovery and dissemination of data and results. We describe the image acquisition pipeline, the pre-processing steps to derive a 2.5D terrain, and a chunked level-of-detail, out-of-core rendering approach to enable interactive exploration of global maps and high-resolution digital terrain models. The results are demonstrated for three different celestial bodies. The first case addresses high-resolution map data on the surface of Mars. A second case is showing dynamic processes. such as concurrent weather conditions on Earth that require temporal datasets. As a final example we use data from the New Horizons spacecraft which acquired images during a single flyby of Pluto. We visualize the acquisition process as well as the resulting surface data. Our work has been implemented in the OpenSpace software [8], which enables interactive presentations in a range of environments such as immersive dome theaters. interactive touch tables. and virtual reality headsets.

  • 13.
    Bleser, Gabriele
    et al.
    Department Augmented Vision, German Research Center for Artificial Intelligence, Kaiserslautern, Germany; Department of Computer Science, Technical University of Kaiserslautern, Kaiserslautern, Germany.
    Damen, Dima
    Department of Computer Science, University of Bristol, Bristol, UK.
    Behera, Ardhendu
    School of Computing, University of Leeds, Leeds, UK; Department of Computing, Edge Hill University, Ormskirk, UK.
    Hendeby, Gustaf
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Mura, Katharina
    SmartFactory KL e.V., Kaiserslautern, Germany.
    Miezal, Markus
    Department of Computer Science, Technical University of Kaiserslautern, Kaiserslautern, Germany.
    Gee, Andrew
    Department of Computer Science, University of Bristol, Bristol, UK.
    Petersen, Nils
    Department Augmented Vision, German Research Center for Artificial Intelligence, Kaiserslautern, Germany.
    Maçães, Gustavo
    Department Computer Vision, Interaction and Graphics, Center for Computer Graphics, Guimarães, Portugal.
    Domingues, Hugo
    Department Computer Vision, Interaction and Graphics, Center for Computer Graphics, Guimarães, Portugal.
    Gorecky, Dominic
    SmartFactory KL e.V., Kaiserslautern, Germany.
    Almeida, Luis
    Department Computer Vision, Interaction and Graphics, Center for Computer Graphics, Guimarães, Portugal.
    Mayol-Cuevas, Walterio
    Department of Computer Science, University of Bristol, Bristol, UK.
    Calway, Andrew
    Department of Computer Science, University of Bristol, Bristol, UK.
    Cohn, Anthony G.
    School of Computing, University of Leeds, Leeds, UK.
    Hogg, David C.
    School of Computing, University of Leeds, Leeds, UK.
    Stricker, Didier
    Department Augmented Vision, German Research Center for Artificial Intelligence, Kaiserslautern, Germany.
    Cognitive Learning, Monitoring and Assistance of Industrial Workflows Using Egocentric Sensor Networks2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 6, e0127769Article in journal (Refereed)
    Abstract [en]

    Today, the workflows that are involved in industrial assembly and production activities are becoming increasingly complex. To efficiently and safely perform these workflows is demanding on the workers, in particular when it comes to infrequent or repetitive tasks. This burden on the workers can be eased by introducing smart assistance systems. This article presents a scalable concept and an integrated system demonstrator designed for this purpose. The basic idea is to learn workflows from observing multiple expert operators and then transfer the learnt workflow models to novice users. Being entirely learning-based, the proposed system can be applied to various tasks and domains. The above idea has been realized in a prototype, which combines components pushing the state of the art of hardware and software designed with interoperability in mind. The emphasis of this article is on the algorithms developed for the prototype: 1) fusion of inertial and visual sensor information from an on-body sensor network (BSN) to robustly track the user’s pose in magnetically polluted environments; 2) learning-based computer vision algorithms to map the workspace, localize the sensor with respect to the workspace and capture objects, even as they are carried; 3) domain-independent and robust workflow recovery and monitoring algorithms based on spatiotemporal pairwise relations deduced from object and user movement with respect to the scene; and 4) context-sensitive augmented reality (AR) user feedback using a head-mounted display (HMD). A distinguishing key feature of the developed algorithms is that they all operate solely on data from the on-body sensor network and that no external instrumentation is needed. The feasibility of the chosen approach for the complete action-perception-feedback loop is demonstrated on three increasingly complex datasets representing manual industrial tasks. These limited size datasets indicate and highlight the potential of the chosen technology as a combined entity as well as point out limitations of the system.

  • 14.
    Bock, Alexander
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Marcinkowski, Michal
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Amer Museum Nat Hist, NY 10024 USA.
    Kilby, Joakim
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Emmart, Carter
    Amer Museum Nat Hist, NY 10024 USA.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    OpenSpace: Public Dissemination of Space Mission Profiles2015In: 2015 IEEE Scientific Visualization Conference (SciVis): Proceedings / [ed] James Ahrens, Huamin Qu, Jos Roerdink, Institute of Electrical and Electronics Engineers (IEEE), 2015, 141-142 p.Conference paper (Refereed)
    Abstract [en]

    This work presents a visualization system and its application to space missions. The system allows the public to disseminate the scientific findings of space craft and gain a greater understanding thereof. Instruments field-of-views and their measurements are embedded in an accurate 3 dimensional rendering of the solar system to provide context to past measurements or the planning of future events. We tested our system with NASAs New Horizons at the Pluto Pallooza event in New York and will expose it to the greater public on the upcoming July 14th Pluto flyby.

  • 15.
    Christiansen, Cecilia
    et al.
    Linköping University, Department of Science and Technology.
    Sandin Värn, Veronica
    Linköping University, Department of Science and Technology.
    Webbaserat system för effektiv registrering och hantering av reklamationer2006Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Vitamex AB är en nordisk egenvårdskoncern med huvudkontor i Norrköping som tillverkar och säljer naturläkemedel och kosttillskott. Inom Vitamex Production AB finns ett reklamationssystem för interna och externa reklamationer som hanteras pappersvägen. För att underlätta hanteringen önskade man ett webbaserat behörighetsstyrt datasystem. I det här examensarbetet beskrivs utvecklingen av ett webbaserat system där fokus har lagts på användbarhet. För utvecklingen har designteorin Usability Engineering använts. Med hjälp av denna process har gränssnittet testats och utvärderats. Rapporten beskriver hur vi lärt känna användarna och uppgiften genom intervjuer. Här beskriver vi hur designprocessen har fungerat genom att låta användarna vara med och påverka genom hela designfasen. Tre prototyper framställdes och dessa presenterades och utvärderades på fokusgrupper. Resultatet har blivit en prototyp med viss interaktivitet och med fokus på användbarhet.

  • 16.
    Dee, Laura E.
    et al.
    University of Minnesota Twin Cities, MN 55108 USA; University of Minnesota Twin Cities, MN 55108 USA.
    Allesina, Stefano
    University of Chicago, IL 60637 USA; University of Chicago, IL 60637 USA.
    Bonn, Aletta
    UFZ Helmholtz Centre Environm Research, Germany; Friedrich Schiller University of Jena, Germany; Gerrnan Centre Integrat Biodivers Research iDiv, Germany.
    Eklöf, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Gaines, Steven D.
    University of Calif Santa Barbara, CA 93117 USA.
    Hines, Jes
    Gerrnan Centre Integrat Biodivers Research iDiv, Germany; University of Leipzig, Germany.
    Jacob, Ute
    Gerrnan Centre Integrat Biodivers Research iDiv, Germany; University of Goettingen, Germany.
    McDonald-Madden, Eve
    University of Queensland, Australia.
    Possingham, Hugh
    University of Queensland, Australia.
    Schroeter, Matthias
    UFZ Helmholtz Centre Environm Research, Germany; Gerrnan Centre Integrat Biodivers Research iDiv, Germany.
    Thompson, Ross M.
    University of Canberra, Australia.
    Operationalizing Network Theory for Ecosystem Service Assessments2017In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 32, no 2, 118-130 p.Article, review/survey (Refereed)
    Abstract [en]

    Managing ecosystems to provide ecosystem services in the face of global change is a pressing challenge for policy and science. Predicting how alternative management actions and changing future conditions will alter services is complicated by interactions among components in ecological and socioeconomic systems. Failure to understand those interactions can lead to detrimental outcomes from management decisions. Network theory that integrates ecological and socioeconomic systems may provide a path to meeting this challenge. While network theory offers promising approaches to examine ecosystem services, few studies have identified how to operationalize networks for managing and assessing diverse ecosystem services. We propose a framework for how to use networks to assess how drivers and management actions will directly and indirectly alter ecosystem services.

  • 17.
    Doyle, Scott
    et al.
    Rutgers University, Dept. of Biomedical Engineering Piscataway, NJ, USA.
    Monaco, James
    Rutgers University, Dept. of Biomedical Engineering Piscataway, NJ, USA.
    Madabhushi, Anant
    Rutgers University, Dept. of Biomedical Engineering Piscataway, NJ, USA.
    Lindholm, Stefan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Siemens Corporate Research,Princeton, NJ, USA.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Siemens Corporate Research,Princeton, NJ, USA.
    Ladic, Lance
    Siemens Corporate Research,Princeton, NJ, USA.
    Tomaszewski, John
    University of Pennsylvania,Dept. of Surgical Pathology Philadelphia, PA, USA.
    Feldman, Michael
    University of Pennsylvania,Dept. of Surgical Pathology Philadelphia, PA, USA.
    Evaluation of effects of JPEG2000 compression on a computer-aided detection system for prostate cancer on digitized histopathology2010In: Biomedical Imaging: From Nano to Macro, 2010 IEEE International Symposium on, 2010, 1313-1316 p.Conference paper (Refereed)
    Abstract [en]

    A single digital pathology image can occupy over 10 gigabytes of hard disk space, rendering it difficult to store, analyze, and transmit. Though image compression provides a means of reducing the storage requirement, its effects on computer-aided diagnosis (CAD) and pathologist performance are not yet clear. In this work we assess the impact of compression on the ability of a CAD system to detect carcinoma of the prostate (CaP) on histological sections. The CAD algorithm proceeds as follows: Glands in the tissue are segmented using a region-growing algorithm, and the size of each gland is extracted. A Markov prior (specifically, a probabilistic pairwise Markov model) is employed to encourage nearby glands to share the same class (i.e. cancerous or non-cancerous). Finally, cancerous glands are aggregated into continuous regions using a distancehull algorithm. We trained the CAD system on 28 images of wholemount histology (WMH) and evaluated performance on 12 images compressed at 14 different compression ratios (a total of 168 experiments) using JPEG2000. Algorithm performance (measured using the under the receiver operating characteristic curves) remains relatively constant for compression ratios up to1 :256, beyond which performance degrades precipitously. For completeness we also have an expert pathologist view a randomly-selected set of compressed images from one of the whole mount studies and assign a confidence measure as to their diagnostic fidelity. Pathologist confidence declined with increasing compression ratio as the information necessary to diagnose the sample was lost, dropping from 100% confidence at ratio 1:64 to 0% at ratio 1:8192.

  • 18.
    Eilert, Rickard
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Development of a framework for creating cross-platform TV HTML5 applications2015Independent thesis Basic level (professional degree), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    When developing HTML5 applications for TV platforms, the TV platforms provide, in addition to standardHTML5 functionality, also extra APIs for TV-specific features. These extra APIs differ between TVplatforms, and that is a problem when developing an application targeting several platforms. This thesis hasexamined if it is possible to design a framework which provides the developer with one API that works formany platforms by wrapping their platform-specific code. The answer is yes. With success, platform-specificfeatures including: TV remote control input, video, volume, Internet connection status, TV channel streamsand EPG data have been harmonised under an API in a JavaScript library. Furthermore, a build systempackages the code in the way the platforms expect. The framework eases the development of TV platformHTML5 applications. At the moment, the framework supports the Pace, PC and Samsung Smart TVplatforms, but it can be extended with more TV platform back-ends.

  • 19.
    Englund, Rickard
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Kottravel, Sathish
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ropinski, Timo
    Visual Computing Research Group, Ulm University.
    A Crowdsourcing System for Integrated and Reproducible Evaluation in Scientific Visualization2016In: 2016 IEEE Pacific Visualization Symposium (PacificVis), IEEE Computer Society, 2016, 40-47 p.Conference paper (Refereed)
    Abstract [en]

    User evaluations have gained increasing importance in visualization research over the past years, as in many cases these evaluations are the only way to support the claims made by visualization researchers. Unfortunately, recent literature reviews show that in comparison to algorithmic performance evaluations, the number of user evaluations is still very low. Reasons for this are the required amount of time to conduct such studies together with the difficulties involved in participant recruitment and result reporting. While it could be shown that the quality of evaluation results and the simplified participant recruitment of crowdsourcing platforms makes this technology a viable alternative to lab experiments when evaluating visualizations, the time for conducting and reporting such evaluations is still very high. In this paper, we propose a software system, which integrates the conduction, the analysis and the reporting of crowdsourced user evaluations directly into the scientific visualization development process. With the proposed system, researchers can conduct and analyze quantitative evaluations on a large scale through an evaluation-centric user interface with only a few mouse clicks. Thus, it becomes possible to perform iterative evaluations during algorithm design, which potentially leads to better results, as compared to the time consuming user evaluations traditionally conducted at the end of the design process. Furthermore, the system is built around a centralized database, which supports an easy reuse of old evaluation designs and the reproduction of old evaluations with new or additional stimuli, which are both driving challenges in scientific visualization research. We will describe the system's design and the considerations made during the design process, and demonstrate the system by conducting three user evaluations, all of which have been published before in the visualization literature.

  • 20.
    Englund, Rickard
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ropinski, Timo
    Visual Computing Research Group, Ulm University.
    Evaluating the perception of semi-transparent structures in direct volume rendering techniques2016In: Proceeding SA '16 SIGGRAPH ASIA 2016 Symposium on Visualization, ACM Digital Library, 2016Conference paper (Refereed)
    Abstract [en]

    Direct volume rendering (DVR) provides the possibility to visualize volumetric data sets as they occur in many scientific disciplines. A key benefit of DVR is that semi-transparency can be facilitated in order to convey the complexity of the visualized data. Unfortunately, semi-transparency introduces new challenges in spatial comprehension of the visualized data, as the ambiguities inherent to semi-transparent representations affect spatial comprehension. Accordingly, many visualization techniques have been introduced to enhance the spatial comprehension of DVR images. In this paper, we conduct a user evaluation in which we compare standard DVR with five visualization techniques which have been proposed to enhance the spatial comprehension of DVR images. In our study, we investigate the perceptual performance of these techniques and compare them against each other to find out which technique is most suitable for different types of data and purposes. In order to do this, a large-scale user study was conducted with 300 participants who completed a number of micro-tasks designed such that the aggregated feedback gives us insight on how well these techniques aid the end user to perceive depth and shape of objects. Within this paper we discuss the tested techniques, present the conducted study and analyze the retrieved results.

  • 21.
    Englund, Rickard
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ropinski, Timo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ultrasound Surface Extraction Using Radial Basis Functions2014In: Advances in Visual Computing: 10th International Symposium, ISVC 2014, Las Vegas, NV, USA, December 8-10, 2014, Proceedings, Part II / [ed] George Bebis, Springer Publishing Company, 2014, Vol. 8888, 163-172 p.Conference paper (Refereed)
    Abstract [en]

    Data acquired from ultrasound examinations is of interest not only for the physician, but also for the patient. While the physician uses the ultrasound data for diagnostic purposes the patient might be more interested in beautiful images in the case of prenatal imaging. Ultrasound data is noisy by nature and visually compelling 3D renderings are not always trivial to produce. This paper presents a technique which enables extraction of a smooth surface mesh from the ultrasound data by combining previous research in ultrasound processing with research in point cloud surface reconstruction. After filtering the ultrasound data using Variational Classification we extract a set of surface points. This set of points is then used to train an Adaptive Compactly Supported Radial Basis Functions system, a technique for surface reconstruction of noisy laser scan data. The resulting technique can be used to extract surfaces with adjustable smoothness and resolution and has been tested on various ultrasound datasets.

  • 22.
    Eriksson, Björn
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Nordin, Peter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Hopsan NG, A C++ Implementation using the TLM Simulation Technique2010In: Proceedings of The 51st Conference on Simulation and Modelling (SIMS2010), Oulu, Finland, 2010Conference paper (Refereed)
    Abstract [en]

    The Hopsan simulation package, used primarily for hydro-mechanical simulation, was first released in 1977. Modeling in Hopsan is based on a method using transmission line modeling, TLM. In TLM, component models are decoupled from each other through time delays. As components are decoupled and use distributed solvers, the simulation environment is suitable for distributed simulations. No numerical errors are introduced at simulation time when using TLM; all errors are related to modeling errors. This yields robust and fast simulations where the size of the time step does not have to be adjusted to achieve a numerically stable simulation. The distributive nature of TLM makes it convenient for use in multi-core approaches and high speed simulations. The latest version of Hopsan was released in August 2002, but now the next generation of this simulation package is being developed. This paper presents the development version of Hopsan NG and discusses some of its features and possible uses.

  • 23. Ernvik, Aron
    et al.
    Bergström, Staffan
    Lundström, Claes
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Ynnerman, Anders
    Linköping University.
    Image data set compression based on viewing parameters for storing medical image data from multidimensional data sets, related systems, methods and computer products2012Patent (Other (popular science, discussion, etc.))
  • 24.
    Galijasevic, Mirza
    et al.
    Linköping University, Department of Electrical Engineering.
    Liedgren, Carl
    Linköping University, Department of Electrical Engineering.
    Efficient content distribution in IPTV environments2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Existing VoD solutions often rely on unicast to distribute content, which leads to a higher load on the VoD server as more nodes become interested in the content. In such case, P2P is an alternative way of distributing content since it makes better use of available resources in the network. In this report, several P2P structures are evaluated from an operators point of view. We believe BitTorrent is the most adequate protocol for a P2P solution in IPTV environments. Two BitTorrent clients have been implemented on an IP-STB as proof of concept to find out whether P2P is suited for IPTV environments. Several tests were conducted to evaluate the performance of both clients and to see if they were able to reach a sufficient throughput on the IP-STB. Based upon the tests and the overall impressions, we are convinced that this particular P2P protocol is well suited for IPTV environments. Hopefully, a client developed from scratch for the IP-STB will offer even greater characteristics.

    Further, we have studied how to share recorded content among IP-STBs. Such a design would probably have many similarities to BitTorrent since a central node needs to keep track of content; the IP-STBs take care of the rest.

    The report also brings up whether BitTorrent is suitable for streaming. We believe that the necessary changes required to obtain such functionality will disrupt the strengths of BitTorrent. Some alternative solutions are presented where BitTorrent has been extended with additional modules, such as a server.

  • 25.
    Garcia Braga, Jose Renato
    et al.
    National Institute for Space Research, Sao Jose dos Campos, SP, Brazil.
    Conte, Gianpaolo
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Doherty, Patrick
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Campos Velho, Haroldo Fraga
    National Institute for Space Research, Sao Jose dos Campos, SP, Brazil.
    Shiguemori, Elcio Hideiti
    Institute of Advanced Studies, Sao Jose dos Campos, SP, Brazil.
    Use of Artificial Neural Networks for Automatic Categorical Change Detection in Satellite Imagery2016In: Proceedings of the 4th Conference of Computational Interdisciplinary Sciences (CCIS 2016), Pan American Association of Computational Interdisciplinary , 2016Conference paper (Other academic)
  • 26.
    Granlund, Gösta H.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    A Nonlinear, Image-content Dependent Measure of Image Quality1977Report (Other academic)
    Abstract [en]

    In recent years, considerable research effort has been devoted to the development of useful descriptors for image quality. The attempts have been hampered by i n complete understanding of the operation of the human visual system. This has made it difficult to relate physical measures and perceptual traits.

    A new model for determination of image quality is proposed. Its main feature is that it tries to invoke image content into consideration. The model builds upon a theory of image linearization, which means that the information in an image can well enough be represented using linear segments or structures within local spatial regions and frequency ranges. This implies a l so a suggestion that information in an image has to do with one- dimensional correlations. This gives a possibility to separate image content from noise in images, and measure them both.

    Also a hypothesis is proposed that the visual system of humans does in fact perform such a linearization.

  • 27.
    Gustavson, Stefan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    2D Shape Rendering by Distance Fields2012In: OpenGL Insights: OpenGL, OpenGL ES, and WebGL community experiences / [ed] Patrick Cozzi and Christophe Riccio, CRC Press, 2012, 173-182 p.Chapter in book (Other academic)
    Abstract [en]

    We present a method for real time rendering of anti-aliased curved contours, combining recent results from research on distance transforms and modern GPU shading using GLSL. The method is capable of rendering glyphs and symbols of very high quality at arbitrary levels of magnification and minification, and it is both versatile and easy to use.

  • 28.
    Gustavson, Stefan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Procedural Textures in GLSL2012In: OpenGL Insights: OpenGL, OpenGL ES and WebGL community experiences / [ed] Patrick Cozzi and Christophe Riccio, CRC Press, 2012, 105-119 p.Chapter in book (Other academic)
    Abstract [en]

    Procedural shading has been a versatile and popular tool for off-line rendering for decades. With the ever increasing speed and computational capabilities of modern GPUs, it is now becoming possible to use procedural shading also for real time rendering. This chapter is an introduction to some classic procedural shading techniques, adapted for real time use.

  • 29.
    Hadwiger, Markus
    et al.
    VRVis Research Center, Vienna, Austria.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Siemens Corporate Research, Princeton, USA.
    Rezk Salama, Christof
    University of Siegen, Germany.
    Ropinski, Timo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. University of M¨unster, Germany.
    Advanced illumination techniques for GPU volume raycasting2008In: ACM Siggraph Asia 2008 Courses, 2008, 1-11 p.Conference paper (Refereed)
    Abstract [en]

    Volume raycasting techniques are important for both visual arts and visualization. They allow an efficient generation of visual effects and the visualization of scientific data obtained by tomography or numerical simulation. Thanks to their flexibility, experts agree that GPU-based raycasting is the state-of-the art technique for interactive volume rendering. It will most likely replace existing slice-based techniques in the near future. Volume rendering techniques are also effective for the direct rendering of implicit surfaces used for soft body animation and constructive solid geometry.

    The lecture starts off with an in-depth introduction to the concepts behind GPU-based ray-casting to provide a common base for the following parts. The focus of this course is on advanced illumination techniques which approximate the physically-based light transport more convincingly. Such techniques include interactive implementation of soft and hard shadows, ambient occlusion and simple Monte-Carlo based approaches to global illumination including translucency and scattering. With the proposed techniques, users are able to interactively create convincing images from volumetric data whose visual quality goes far beyond traditional approaches. The optical properties in participating media are defined using the phase function. Many approximations to the physically based light transport applied for rendering natural phenomena such as clouds or smoke assume a rather homogenous phase function model. For rendering volumetric scans on the other hand different phase function models are required to account for both surface-like structures and fuzzy boundaries in the data. Using volume rendering techniques, artists who create medical visualization for science magazines may now work on tomographic scans directly, without the necessity to fall back to creating polygonal models of anatomical structures.

  • 30.
    Hadwiger, Markus
    et al.
    VRVis Research Center, Vienna, Austria.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Siemens Corporate Research, Princeton, USA.
    Rezk-Salama, Christof
    University of Siegen, Germany.
    Ropinski, Timo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. University of Münster, Germany.
    Advanced Illumination Techniques for GPU-Based Volume Raycasting2009Other (Other academic)
    Abstract [en]

    Volume raycasting techniques are important for both visual arts and visualization. They allow an efficient generation of visual effects and the visualization of scientific data obtained by tomography or numerical simulation. Thanks to their flexibility, experts agree that GPU-based raycasting is the state-of-the art technique for interactive volume rendering. It will most likely replace existing slice-based techniques in the near future. Volume rendering techniques are also effective for the direct rendering of implicit surfaces used for soft body animation and constructive solid geometry.

    The lecture starts off with an in-depth introduction to the concepts behind GPU-based ray-casting to provide a common base for the following parts. The focus of this course is on advanced illumination techniques which approximate the physically-based light transport more convincingly. Such techniques include interactive implementation of soft and hard shadows, ambient occlusion and simple Monte-Carlo based approaches to global illumination including translucency and scattering. With the proposed techniques, users are able to interactively create convincing images from volumetric data whose visual quality goes far beyond traditional approaches. The optical properties in participating media are defined using the phase function. Many approximations to the physically based light transport applied for rendering natural phenomena such as clouds or smoke assume a rather homogenous phase function model. For rendering volumetric scans on the other hand different phase function models are required to account for both surface-like structures and fuzzy boundaries in the data. Using volume rendering techniques, artists who create medical visualization for science magazines may now work on tomographic scans directly, without the necessity to fall back to creating polygonal models of anatomical structures.

  • 31.
    Hagström, Åsa
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Understanding Certificate Revocation2006Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Correct certificate revocation practices are essential to each public-key infrastructure. While there exist a number of protocols to achieve revocation in PKI systems, there has been very little work on the theory behind it: Which different types of revocation can be identified? What is the intended effect of a specific revocation type to the knowledge base of each entity?

    As a first step towards a methodology for the development of reliable models, we present a graph-based formalism for specification and reasoning about the distribution and revocation of public keys and certificates. The model is an abstract generalization of existing PKIs and distributed in nature; each entity can issue certificates for public keys that they have confidence in, and distribute or revoke these to and from other entities.

    Each entity has its own public-key base and can derive new knowledge by combining this knowledge with certificates signed with known keys. Each statement that is deduced or quoted within the system derives its support from original knowledge formed outside the system. When such original knowledge is removed, all statements that depended upon it are removed as well. Cyclic support is avoided through the use of support sets.

    We define different revocation reasons and show how they can be modelled as specific actions. Revocation by removal, by inactivation, and by negation are all included. By policy, negative statements are the strongest, and positive are the weakest. Collisions are avoided by removing the weaker statement and, when necessary, its support.

    Graph transformation rules are the chosen formalism. Rules are either interactive changes that can be applied by entities, or automatically applied deductions that keep the system sound and complete after the application of an interactive rule.

    We show that the proposed model is sound and complete with respect to our definition of a valid state.

  • 32.
    Hassan, Waqar Ul
    Linköping University, Department of Computer and Information Science.
    Pixel Based and Object Oriented Multi-spectral Remotely Sensed Data Analysis for Flood Risk Assessment and Vulnerability Mapping.2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Geographical information system with remotely sensed data can be instrumental in many ways for disaster management and post disaster rehabilitation. During last few decades the usage of remotely sensed data has extensively increased, although image interpretation tools are not highly accurate but still considered as fast, reliable and useful way to get information from imagery. Disaster assessment, management and rehabilitation are always creates challenge for experts. Population growth, expansion in settlements either in the rural or in the urban areas bring more problems not only for the humans but it also affect the global environment Such global changes on the massive scale disturbs the ecological processes. GIS along with Remote sensing data can change the whole scenario in very short period of time. All the departments concerning to strategic disaster planning process can share their information by using the single platform, so for this purpose spatial database can be helpful by providing the spatial data in digital format to the department concerned. Spatial phenomena can be observed by using different image analysis techniques and the resultant thematic map display the spatial variations and changes that describe the particular phenomenon whether it was any disaster or change in soil type or vegetation type. Remotely sensed data like aerial, satellite and radar images are very useful for disaster management strategy formulation process. Integration of GIS and remote sensing proved itself the best especially for land-use, land-cover mapping. For this purpose pixel based, sub-pixel based, pre-field and object oriented classification approach are being in use around the world. But thematic maps created from image analyzed by using object oriented classifiers contain more accuracy than any other techniques.

  • 33.
    Heintz, Fredrik
    et al.
    Linköping University, Department of Computer and Information Science, KPLAB - Knowledge Processing Lab. Linköping University, The Institute of Technology.
    Erlander Klein, Inger
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Civilingenjör i Mjukvaruteknik vid Linköpings universitet: mål, design och erfarenheter2013In: Proceedings of 4:de Utvecklingskonferensen för Sveriges ingenjörsutbildningar (UtvSvIng) / [ed] S. Vikström, R. Andersson, F. Georgsson, S. Gunnarsson, J. Malmqvist, S. Pålsson och D. Raudberget, 2013Conference paper (Refereed)
    Abstract [en]

    Hösten 2013 startade Linköpings universitet den första civilingenjörsutbildningen i Mjukvaruteknik. Utbildningens mål är att bland annat att ge ett helhetsperspektiv på modern storskalig mjukvaruutveckling, ge en gedigen grund i datavetenskap och computational thinking samt främja entreprenörskap och innovation. Studenternas gensvar har varit över förväntan med över 600 sökande till de 30 platserna varav 134 förstahandssökande. Här presenterar vi programmets vision, mål, designprinciper samt det färdiga programmet. En viktig förebild är ACM/IEEE Computer Science Curricula som precis kommit i en ny uppdaterad version. Tre pedagogiska idéer vi har följt är (1) att använda projektkurser för att integrera teori och praktik samt ge erfarenhet i den vanligaste arbetsformen i näringslivet; (2) att undervisa i flera olika programspråk och flera olika programutvecklingsmetodiker för att ge en plattform att ta till sig det senaste på området; och (3) att införa en programsammanhållande kurs i ingenjörsprofessionalism i årskurs 1–3 som ger studenterna verktyg att reflektera över sitt eget lärande, att jobba i näringslivet samt sin professionella yrkesroll. Artikeln avslutas med en diskussion om viktiga aspekter som computational thinking och ACM/IEEE CS Curricula.

  • 34.
    Heintz, Fredrik
    et al.
    Linköping University, Department of Computer and Information Science, KPLAB - Knowledge Processing Lab. Linköping University, The Institute of Technology.
    Erlander Klein, Inger
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    The Design of Sweden's First 5-year Computer Science and Software Engineering Program2014In: Proceedings of the 45th ACM Technical Symposium on Computer Science Education (SIGCSE 2014), ACM Press, 2014, 199-204 p.Conference paper (Refereed)
  • 35.
    Heintz, Fredrik
    et al.
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Intergrated Computer systems. Linköping University, The Institute of Technology.
    Färnqvist, Tommy
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Återkoppling genom automaträttning2013In: Proceedings of 4:de Utvecklingskonferensen för Sveriges ingenjörsutbildningar (UtvSvIng), 2013Conference paper (Refereed)
    Abstract [sv]

    Vi har undersökt olika former av återkoppling genom automaträttning i en kurs i datastrukturer och algoritmer. 2011 undersökte vi effekterna av tävlingsliknande moment som också använder automaträttning. 2012 införde vi automaträttning av laborationerna. Vi undersökte då hur återkoppling genom automaträttning påverkar studenternasarbetssätt, prestationsgrad och relation till den examinerande personalen. Genom automaträttning får studenterna omedelbar återkoppling om deras program är tillräckligt snabbt och ger rätt svar på testdata. När programmet är korrekt och resurseffektivt kontrollerar kursassistenterna att programmet även uppfyller andra krav som att vara välskrivet och välstrukturerat. Efter kursen undersökte vi studenternas inställning till och upplevelse av automaträttning genom en enkät. Resultaten är att studenterna är positiva till automaträttning (80% av alla som svarade) och att den påverkade studenternas sätt att arbeta huvudsakligen positivt. Till exempel svarade 50% att de ansträngde sig hårdare tack vare automaträttningen. Dessutom blir rättningen mer objektiv då den görs på exakt samma sätt för alla. Vår slutsats är att återkoppling genom automaträttning ger positiva effekter och upplevs som positiv av studenterna.

  • 36.
    Hellgren, Marcus
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Enbrant, Ida
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Vilken Open Source SIP-server lämpar sig bäst förAndroid?2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Denna studie tacklar ett av de problem som modern IP-telefoni brottas med, som gör att det är svårare att konkurrera med traditionell telefoni: fördröjningar på grund av otillräckliga Session Initiation Protocol-servrar (SIP). Genom tester av de viktigaste faktorerna jämförs fyra högaktuella Open Source SIP-servrar: OpenSIPS, Kamailio, FreeSWITCH och Yate. Avsikten är att underlätta valet av SIP-server för nya applikationer inom IP-telefoni, öka prestandan samt snabba på utvecklingen. Studien behandlar de intressantaste faktorerna vid val SIP, såsom användarvänlighet, hastighet, lagring av användardata samt ljudkvalité. Slutsatsen blev att Kamailio stod som klar segrare, med överlägsna resultat i jämförelse med övriga servrar, på de parametrar som valts ut. Skillnaderna var förhållandevis små prestandamässigt – det som verkligen avgjorde var främst hur avancerade servrarna var att installera, använda samt konfigurera.

  • 37.
    Hernell, Frida
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Local ambient occlusion in direct volume rendering2010In: Visualization and Computer Graphics, IEEE Transactions on, ISSN 1077-2626, Vol. 16, no 4, 548-559 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel technique to efficiently compute illumination for Direct Volume Rendering using a local approximation of ambient occlusion to integrate the intensity of incident light for each voxel. An advantage with this local approach is that fully shadowed regions are avoided, a desirable feature in many applications of volume rendering such as medical visualization.

    Additional transfer function interactions are also presented, for instance, to highlight specific structures with luminous tissue effects and create an improved context for semitransparent tissues with a separate absorption control for the illumination settings. Multiresolution volume management and GPU-based computation are used to accelerate the calculations and support large data sets. The scheme yields interactive frame rates with an adaptive sampling approach for incrementally refined illumination under arbitrary transfer function changes. The illumination effects can give a better understanding of the shape and density of tissues and so has the potential to increase the diagnostic value of medical volume rendering. Since the proposed method is gradient-free, it is especially beneficial at the borders of clip planes, where gradients are undefined, and for noisy data sets.

  • 38.
    Ho, Quan
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Jern, Mikael
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Exploratory 3D Geovisual Analytics2008In: 2008 IEEE International Conference on Research, Innovation and Vision for the Future in Computing Communications Technologies,2008 / [ed] Tru Cao, Tu-Bao Ho, P. O. Box 1331, 445 Hoes Lane, Piscataway, NJ 08855-1331 USA: IEEE Operations Center , 2008, 276-283 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we extend our generic -GeoAnalytics- visualization (GAV) component toolkit, based on the principles behind Visual Analytics (VA), to also support time-oriented, geographically referenced and multivariate attribute volumetric data. GAV includes components that support a mixture of technologies from the three data visualization fields: information visualization (InfoVis), geovisualization (GeoVis) and scientific visualization (SciVis). Our research concentrates on visual user interface (VUI) techniques through dynamic and direct data manipulation that permit the visual analytical process to become more interactive and focused. This paper encourages synergies between well-known information- and volume data visualization methods applied in a multiple-linked and coordinated views interface. We address challenges for improved data interaction techniques with volumetric data and the need for immediate response. Varieties of explorative data analysis (EDA) tasks and the possibility to view the information simultaneously from different perspectives and scenarios are discussed. The effectiveness of our geovisual analytics framework is demonstrated in a tailor-made volume data explorer (VDE) application that integrates InfoVis, GeoVis and SciVis visualization methods assembled from GAV components. VDE facilitates dynamic exploration and correlation of temporal ocean space temperature and salinity data supplied in a NetCDF format from NOAA. This real-world phenomenon that corresponds to a huge volumetric data set comprises more than 31 million values for a time period of 12 months in 1994.

  • 39.
    Ho, Quan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lundblad, Patrik
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Åström, Tobias
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Jern, Mikael
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    A Web-Enabled Visualization Toolkit for Geovisual Analytics2012In: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 11, no 1, 22-42 p.Article in journal (Refereed)
    Abstract [en]

    A framework and class library (GAV Flash) implemented in Adobe’s ActionScript is introduced, designed with the intention to significantly shorten the time and effort needed to develop customized web-enabled applications for geovisual analytics tasks. Through an atomic layered component architecture, GAV Flash provides a collection of interactive geo- and information visualization representations for exploring high dimensional spaces and extended with motion behavior. Versatile interaction methods are drawn from many data visualization research areas and optimized for dynamic web visualization of spatio-temporal and multivariate data. Based on layered component thinking and the use of programming interface mechanism the GAV Flash architecture is open and facilitates the creation of new or improved versions of existing components so that ideas can be tried out or optimized rapidly in a fully functional environment. Not only is GAV Flash a tool for interactive visualization but also supports storytelling around visual analytics in which visual representations not only serve as a discovery tool for individuals but also as a mean to share stories among users fostering a social style of collaborative data analysis. A mechanism “snapshot” for saving the explorative results of a reasoning process is introduced that aids collaboration and publication of gained insight and knowledge embedded as dynamic visualizations in blogs or web pages with associative metadata or “storytelling”.

  • 40.
    Ho, Quan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lundblad, Patrik
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Åström, Tobias
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Jern, Mikael
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    A Web-Enabled Visualization Toolkit for Geovisual Analytics2011In: Proceedings of SPIE, the International Society for Optical Engineering: SPIE: Electronic Imaging Science and Technology, Visualization and Data Analysis / [ed] Chung Wong, Pak; Park, Jinah; Hao, Ming C.; Chen, Chaomei; Börner, Katy; Kao, David L.; Roberts, Jonathan C., SPIE, Bellingham WA, ETATS-UNIS: SPIE - International Society for Optical Engineering, 2011, 78680R-78680R-12 p.Conference paper (Refereed)
    Abstract [en]

    We introduce a framework and class library (GAV Flash) implemented in Adobe’s ActionScript, designed with the intention to significantly shorten the time and effort needed to develop customized web-enabled applications for visual analytics or geovisual analytics tasks. Through an atomic layered component architecture, GAV Flash provides a collection of common geo- and information visualization representations extended with motion behavior including scatter matrix, extended parallel coordinates, table lens, choropleth map and treemap, integrated in a multiple, time-linked layout. Versatile interaction methods are drawn from many data visualization research areas and optimized for dynamic web visualization of spatio-temporal and multivariate data. Based on layered component thinking and the use of programming interface mechanism the GAV Flash architecture is open and facilitates the creation of new or improved versions of existing components so that ideas can be tried out or optimized rapidly in a fully functional environment. Following the Visual Analytics mantra, a mechanism “snapshot” for saving the explorative results of a reasoning process is developed that aids collaboration and publication of gained insight and knowledge embedded as dynamic visualizations in blogs or web pages with associative metadata or “storytelling”.

  • 41.
    Ho, Quan
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Åström, Tobias
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Jern, Mikael
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Geovisual Analytics for Self-Organizing Network Data2009In: Proceedings of IEEE Symposium on Visual Analytics Science and Technology, 2009 (VAST 2009 / [ed] John Stasko, Jarke J. van Wijk, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331 USA: IEEE Service Center , 2009, 43-50 p.Conference paper (Refereed)
    Abstract [en]

    Cellular radio networks are continually growing in both node count and complexity. It therefore becomes more difficult to manage the networks and necessary to use time and cost effective automatic algorithms to organize the network’s neighbor cell relations. There have been a number of attempts to develop such automatic algorithms. Network operators, however, may not trust them because they need to have an understanding of their behavior and of their reliability and performance, which is not easily perceived. This paper presents a novel web-enabled geovisual analytics approach to exploration and understanding of self-organizing network data related to cells and neighbor cell relations. A demonstrator and case study are presented in this paper, developed in close collaboration with the Swedish telecom company Ericsson and based on large multivariate, time-varying and geospatial data provided by the company. It allows the operators to follow, interact with and analyze the evolution of a self-organizing network and enhance their understanding of how an automatic algorithm configures locally-unique physical cell identities and organizes neighbor cell relations of the network. The geovisual analytics tool is tested with a self-organizing network that is operated by the Automatic Neighbor Relations (ANR) algorithm. The demonstrator has been tested with positive results by a group of domain experts from Ericsson and will be tested in production.

  • 42.
    Ho, Quan
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Åström, Tobias
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Jern, Mikael
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Moe, Johan
    Wireless Access Networks, Ericsson Research, Ericsson AB, Sweden.
    Gunnarsson, Fredrik
    Wireless Access Networks, Ericsson Research, Ericsson AB, Sweden.
    Kallin, Harald
    Wireless Access Networks, Ericsson Research, Ericsson AB, Sweden.
    Visualization of Self-Organizing NetworksOperated by the ANR Algorithm2009In: 2009 IEEE-RIVF International Conference on Computing and Communication Technologies: Research, Innovation and Vision for the Future / [ed] Tru Cao, Ralf-Detlef Kutsche, Akim Demaille, Piscataway, NJ, USA: IEEE , 2009, 312-319 p.Conference paper (Refereed)
    Abstract [en]

    Cellular radio networks are continually growing in both node count and complexity. It therefore becomes more and more difficult to manage the networks and necessary to use time and cost effective automatic computer algorithms to organize the network’s neighbor cell relations. Ericsson has developed such an algorithm, called Automatic Neighbor Relations (ANR), which solves a part of this problem by automatically creating and updating neighbor cell relation (NCR) lists, based on measured network data. Network operators need to have an understanding of the algorithm and of its reliability and performance, which is not easily perceived. This paper presents a visualization tool that visualizes the performance of ANR and gives the user a possibility to control it via policies. The tool allows the operators to follow the evolution of the network and to find problems occurring over time. In addition, it also supports finding potential problems that can occur in the future. The tool was evaluated by a group of relevant domain users and the results from the evaluation were highly positive.

  • 43.
    Ivády, Viktor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Development of theoretical approaches for post-silicon information processing2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Despite knowing the fundamental equations in most of the physics research areas, still there is an unceasing need for theoretical method development, thanks to the more and more challenging problems addressed by the research community. The investigation of post-silicon, non-classical information processing is one of the new and rapidly developing areas that requires tremendous amount of theoretical support, new understanding, and accurate theoretical predictions. My thesis focuses on theoretical method development for solid-state quantum information processing, mainly in the field of point defect quantum bits (qubits) in silicon carbide (SiC) and diamond. Due to recent experimental breakthroughs in this field, there are diverse theoretical problems, ranging from functional development for accurate first principles description of point defects, through complete theoretical characterization of qubits, to the modeling and simulation of actual quantum information protocols, that are needed to be addressed. The included articles of this thesis cover the development of (i) hybrid-DFT+Vw approach for the first principles description of mixed correlated and uncorrelated systems, (ii) zero-field-splitting tensor calculation for solid-state quantum bit characterization, (iii) a comprehensive model for dynamic nuclear spin polarization of solid-state qubits in semiconductors, and (iv) group theoretical description of qubits and novel twodimensional materials for topologically protected states.

    List of papers
    1. Theoretical unification of hybrid-DFT and DFT plus U methods for the treatment of localized orbitals
    Open this publication in new window or tab >>Theoretical unification of hybrid-DFT and DFT plus U methods for the treatment of localized orbitals
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    2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 3, 035146- p.Article in journal (Refereed) Published
    Abstract [en]

    Hybrid functionals serve as a powerful practical tool in different fields of computational physics and quantum chemistry. On the other hand, their applicability for the case of correlated d and f orbitals is still questionable and needs more considerations. In this article we formulate the on-site occupation dependent exchange correlation energy and effective potential of hybrid functionals for localized states and connect them to the on-site correction term of the DFT+ U method. The resultant formula indicates that the screening of the onsite electron repulsion is governed by the ratio of the exact exchange in hybrid functionals. Our derivation provides a theoretical justification for adding a DFT+ U-like on-site potential in hybrid-DFT calculations to resolve issues caused by overscreening of localized states. The resulting scheme, hybrid DFT+ V-w, is tested for chromium impurity in wurtzite AlN and vanadium impurity in 4H-SiC, which are paradigm examples of systems with different degrees of localization between host and impurity orbitals.

    Place, publisher, year, edition, pages
    American Physical Society, 2014
    National Category
    Physical Sciences Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-109879 (URN)10.1103/PhysRevB.90.035146 (DOI)000339974700005 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation "Isotopic Control for Ultimate Materials Properties"; Swedish Research Council (VR) Grants [621-2011-4426, 621-2011-4249]; Swedish Foundation for Strategic Research program SRL Grant [10-0026]; Swedish National Infrastructure for Computing Grants [SNIC 001/12-275, SNIC 2013/1-331]; "Lendulet program" of Hungarian Academy of Sciences; U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-AC02-06CH11357]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials (LiLi-NFM) - VR

    Available from: 2014-08-28 Created: 2014-08-28 Last updated: 2017-12-05
    2. Role of screening in the density functional applied to transition-metal defects in semiconductors
    Open this publication in new window or tab >>Role of screening in the density functional applied to transition-metal defects in semiconductors
    2013 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 20Article in journal (Refereed) Published
    Abstract [en]

    We study selected transition-metal-related point defects in silicon and silicon carbide semiconductors by a range-separated hybrid density functional (HSE06). We find that HSE06 does not fulfill the generalized Koopmans' theorem for every defect, which is due to the self-interaction error in the functional in such cases. Restoring the so-called generalized Koopmans' condition with a simple correction in the functional can eliminate this error and brings the calculated charge transition levels remarkably close to the experimental data as well as to the calculated quasiparticle levels from many-body perturbation theory.

    Place, publisher, year, edition, pages
    American Physical Society, 2013
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-93859 (URN)10.1103/PhysRevB.87.205201 (DOI)000318521500002 ()
    Note

    Funding Agencies|Swedish Foundation for Strategic Research||Swedish Research Council||Swedish Energy Agency||Swedish National Infrastructure for Computing|SNIC 011/04-8SNIC001-10-223|Knut & Alice Wallenberg Foundation||EU||European Science Foundation for Advanced Concepts in ab-initio Simulations of Materials||

    Available from: 2013-06-11 Created: 2013-06-11 Last updated: 2017-12-06
    3. Pressure and temperature dependence of the zero-field splitting in the ground state of NV centers in diamond: A first-principles study
    Open this publication in new window or tab >>Pressure and temperature dependence of the zero-field splitting in the ground state of NV centers in diamond: A first-principles study
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    2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 23, 235205- p.Article in journal (Refereed) Published
    Abstract [en]

    Nitrogen-vacancy centers in diamond (NV) attract great attention because they serve as a tool in many important applications. The NV center has a polarizable spin S = 1 ground state and its spin state can be addressed by optically detected magnetic resonance (ODMR) techniques. The m(S) = 0 and m(S) = +/- 1 spin levels of the ground state are separated by about 2.88 GHz in the absence of an external magnetic field or any other perturbations. This zero-field splitting (ZFS) can be probed by ODMR. As this splitting changes as a function of pressure and temperature, the NV center might be employed as a sensor operating at the nanoscale. Therefore, it is of high importance to understand the intricate details of the pressure and temperature dependence of this splitting. Here we present an ab initio theory of the ZFS of the NV center as a function of external pressure and temperature including detailed analysis on the contributions of macroscopic and microscopic effects. We found that the pressure dependence is governed by the change in the distance between spins as a consequence of the global compression and the additional local structural relaxation. The local structural relaxation contributes to the change of ZFS with the same magnitude as the global compression. In the case of temperature dependence of ZFS, we investigated the effect of macroscopic thermal expansion as well as the consequent change of the microscopic equilibrium positions. We could conclude that theses effects are responsible for about 15% of the observed decrease of ZFS.

    Place, publisher, year, edition, pages
    American Physical Society, 2014
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-113573 (URN)10.1103/PhysRevB.90.235205 (DOI)000346860700002 ()
    Note

    Funding Agencies|NIIF Supercomputer center [1090]; EU [270197, 611143]; Hungarian Academy of Sciences; Knut and Alice Wallenberg Foundation; Swedish National Infrastructure for Computing [SNIC 001/12-275, SNIC 2013/1-331]; Conicyt (Chile) Fondecyt [1141185, PIA ACT1108, PIA ACT1112]; Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]; Tomsk State University

    Available from: 2015-01-23 Created: 2015-01-23 Last updated: 2017-12-05
    4. Theoretical model of dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide
    Open this publication in new window or tab >>Theoretical model of dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide
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    2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 11, 115206- p.Article in journal (Refereed) Published
    Abstract [en]

    Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point defects in semiconductors is a key resource for both initializing nuclear quantum memories and producing nuclear hyperpolarization. DNP is therefore an important process in the field of quantum-information processing, sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based spintronics. DNP based on optical pumping of point defects has been demonstrated by using the electron spin of nitrogen-vacancy (NV) center in diamond, and more recently, by using divacancy and related defect spins in hexagonal silicon carbide (SiC). Here, we describe a general model for these optical DNP processes that allows the effects of many microscopic processes to be integrated. Applying this theory, we gain a deeper insight into dynamic nuclear spin polarization and the physics of diamond and SiC defects. Our results are in good agreement with experimental observations and provide a detailed and unified understanding. In particular, our findings show that the defect electron spin coherence times and excited state lifetimes are crucial factors in the entire DNP process.

    Place, publisher, year, edition, pages
    AMER PHYSICAL SOC, 2015
    National Category
    Physical Sciences Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-121891 (URN)10.1103/PhysRevB.92.115206 (DOI)000361370600003 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation "Isotopic Control for Ultimate Materials Properties"; Swedish Research Council (VR) [621-2011-4426, 621-2011-4249]; Swedish Foundation for Strategic Research program SRL [10-0026]; Grant of Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]; Tomsk State University Academic D. I. Mendeleev Fund Program [8.1.18.2015]; Swedish National Infrastructure for Computing Grants [SNIC 2013/1-331]; "Lendulet program" of Hungarian Academy of Sciences

    Available from: 2015-10-13 Created: 2015-10-12 Last updated: 2017-12-01
    5. Optical Polarization of Nuclear Spins in Silicon Carbide
    Open this publication in new window or tab >>Optical Polarization of Nuclear Spins in Silicon Carbide
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    2015 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 114, no 24, 247603- p.Article in journal (Refereed) Published
    Abstract [en]

    We demonstrate optically pumped dynamic nuclear polarization of Si-29 nuclear spins that are strongly coupled to paramagnetic color centers in 4H- and 6H-SiC. The 99% +/- 1% degree of polarization that we observe at room temperature corresponds to an effective nuclear temperature of 5 mu K. By combining ab initio theory with the experimental identification of the color centers optically excited states, we quantitatively model how the polarization derives from hyperfine-mediated level anticrossings. These results lay a foundation for SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for magnetic resonance imaging.

    Place, publisher, year, edition, pages
    American Physical Society, 2015
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-120166 (URN)10.1103/PhysRevLett.114.247603 (DOI)000356407600010 ()
    Note

    Funding Agencies|Air Force Office of Scientific Research (AFOSR); AFOSR Multidisciplinary Research Program of the University Research Initiative; National Science Foundation; Material Research Science and Engineering Center; Knut and Alice Wallenberg Foundation "Isotopic Control for Ultimate Materials Properties"; Lendulet program of the Hungarian Academy of Sciences; National Supercomputer Center in Sweden

    Available from: 2015-07-13 Created: 2015-07-13 Last updated: 2017-12-04
    6. A silicon carbide room-temperature single-photon source
    Open this publication in new window or tab >>A silicon carbide room-temperature single-photon source
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    2014 (English)In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 13, no 2, 151-156 p.Article in journal (Refereed) Published
    Abstract [en]

    Over the past few years, single-photon generation has been realized in numerous systems: single molecules(1), quantum dots(2-4), diamond colour centres5 and others(6). The generation and detection of single photons play a central role in the experimental foundation of quantum mechanics(7) and measurement theory(8). An efficient and high-quality single-photon source is needed to implement quantum key distribution, quantum repeaters and photonic quantum information processing(9). Here we report the identification and formation of ultrabright, room-temperature, photostable single-photon sources in a device-friendly material, silicon carbide (SiC). The source is composed of an intrinsic defect, known as the carbon antisite-vacancy pair, created by carefully optimized electron irradiation and annealing of ultrapure SiC. An extreme brightness (2 x 10(6) counts s(-1)) resulting from polarization rules and a high quantum efficiency is obtained in the bulk without resorting to the use of a cavity or plasmonic structure. This may benefit future integrated quantum photonic devices(9).

    Place, publisher, year, edition, pages
    Nature Publishing Group, 2014
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104643 (URN)10.1038/nmat3806 (DOI)000330182700020 ()
    Available from: 2014-02-20 Created: 2014-02-20 Last updated: 2017-12-06
    7. Dirac points with giant spin-orbit splitting in the electronic structure of two-dimensional transition-metal carbides
    Open this publication in new window or tab >>Dirac points with giant spin-orbit splitting in the electronic structure of two-dimensional transition-metal carbides
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    2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 15Article in journal (Refereed) Published
    Abstract [en]

    We investigated the structural and electrical properties of 2D MXene sheets by means of firstprinciples density functional theory (DFT) calculations. To describe the Kohn-Sham states, plane wave basis set and projector augmented wave method (PAW) were used as implemented in the Vienna ab initio Simulation Package (VASP). We applied PBE parameterization of the generalized gradient approximation of the exchange and correlation energy functional to account for many-body effects of the interacting electron system. Convergent sampling of the Brillouin-zone was achieved by a Γ-centered 15×15×1 grid. In order to model a single sheet of MXene we ensured at least 30 Å vacuum between the periodically repeated sheets. For the structural optimization 1×10−3 eV/Å force criteria was used. The relativistic spin-orbit coupling effects were also included in our simulations regarding band structure and density of states.

    Keyword
    Cone-point, MAX phase, MXene, Dirac fermion, Spin-orbit coupling
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-113761 (URN)10.1103/PhysRevB.92.155142 (DOI)000363512700002 ()
    Available from: 2015-05-01 Created: 2015-01-30 Last updated: 2017-12-05Bibliographically approved
  • 44.
    Joakim, Valberg
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Intergrated Computer systems.
    Document Separation in Digital Mailrooms2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The growing mail volumes for businesses worldwide is one reason why theyare increasingly turning to digital mailrooms. A digital mailroom automaticallymanages the incoming mails, and a vital technology to its success isdocument classication. A problem with digital mailrooms and the documentclassication is separating the input stream of pages into documents.This thesis investigates existing classication theory and applies it to createan algorithm which solves the document separation problem. This algorithmis evaluated and compared against an existing algorithmic solution, over adataset containing real invoices.

  • 45.
    Johansson, Gustaf
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Regularization in Medical Image Registration using Global Linear OptimizationManuscript (preprint) (Other academic)
    Abstract [en]

    Common problems in image registration include having large parts of the images contain noisy, uncertain, missing or impossible motion. Regularization is the field that aims to overcome these problems. In this article, we propose a novel framework : Global Linear Optimization (GLO) which we demonstrate has the capabilities to simultaneously and globally regularize with respect to : (1) anisotropic certainty of prior motion field, (2) sliding of organ boundaries and (3) incompressibility of organ interiors. The power of the presented framework consists of being able to spatially adapt which subsets of the data each constraint should affect and then solve a large sparse linear equations system which automatically propagates a solution over the data set through an overlapping localized metric. We demonstrate the validity of the methods and the power of the GLO framework on relevant test cases and on medical data from the DIR-lab.

  • 46.
    Johansson, Hanna
    Linköping University, Department of Management and Engineering, Environmental Technology and Management.
    Interdisciplinary Requirement Engineering for Hardware and Software Development: from a Hardware Development Perspective2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Complexity in products is increasing, and still there is lack of a shared design language ininterdisciplinary development projects. The research questions of the thesis concern differencesand similarities in requirement handling, and integration, current and future. Futureintegration is given more focus with a pair of research questions highlighting obstacles andenablers for increased integration. Interviews were performed at four different companieswith complex development environments whose products originated from different fields;hardware, software, and service. Main conclusions of the thesis are: Time-frames in different development processes are very different and hard to unite. Internal standards exist for overall processes, documentation, and modification handling. Traceability is poorly covered in theory whilst being a big issue in companies. Companies understand that balancing and compromising of requirements is critical fora successful final product. The view on future increased interdisciplinary development is that there are more obstaclesto overcome than enablers supporting it. Dependency is seen as an obstacle inthis regard and certain companies strive to decrease it.The thesis has resulted in general conclusions and further studies is suggested into morespecific areas such as requirement handling tools, requirement types, and traceability.

  • 47.
    Johansson, Jimmy
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Navarra, Carlo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Schmid Neset, Tina
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Glaas, Erik
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Opach, Tomasz
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Norwegian University of Science and Technology, Norway.
    Björn-Ola, Linnér
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    VisAdapt-Increasing Nordic Houseowners' Adaptive Capacity to Climate Change2014In: 2014 IEEE Conference on Visual Analytics Science and Technology (VAST) / [ed] Min Chen, David Ebert, Chris North, Institute of Electrical and Electronics Engineers (IEEE), 2014, 255-256 p.Conference paper (Refereed)
    Abstract [en]

    This poster presents the design and implementation of the web-based visual analytics tool VisAdapt which allows houseowners in the Nordic countries to assess potential climate related risk factors that may have an impact on their living conditions, and to get an overview of existing guidelines of how to adapt to climate change and extreme weather effects.

  • 48.
    Jönsson, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Enhancing Salient Features in Volumetric Data Using Illumination and Transfer Functions2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The visualization of volume data is a fundamental component in the medical domain. Volume data is used in the clinical work-flow to diagnose patients and is therefore of uttermost importance. The amount of data is rapidly increasing as sensors, such as computed tomography scanners, become capable of measuring more details and gathering more data over time. Unfortunately, the increasing amount of data makes it computationally challenging to interactively apply high quality methods to increase shape and depth perception. Furthermore, methods for exploring volume data has mostly been designed for experts, which prohibits novice users from exploring volume data. This thesis aims to address these challenges by introducing efficient methods for enhancing salient features through high quality illumination as well as methods for intuitive volume data exploration.

    Humans are interpreting the world around them by observing how light interacts with objects. Shadows enable us to better determine distances while shifts in color enable us to better distinguish objects and identify their shape. These concepts are also applicable to computer generated content. The perception in volume data visualization can therefore be improved by simulating real-world light interaction. This thesis presents efficient methods that are capable of interactively simulating realistic light propagation in volume data. In particular, this work shows how a multi-resolution grid can be used to encode the attenuation of light from all directions using spherical harmonics and thereby enable advanced interactive dynamic light configurations. Two methods are also presented that allow photon mapping calculations to be focused on visually changing areas.The results demonstrate that photon mapping can be used in interactive volume visualization for both static and time-varying volume data.

    Efficient and intuitive exploration of volume data requires methods that are easy to use and reflect the objects that were measured. A value that has been collected by a sensor commonly represents the material existing within a small neighborhood around a location. Recreating the original materials is difficult since the value represents a mixture of them. This is referred to as the partial-volume problem. A method is presented that derives knowledge from the user in order to reconstruct the original materials in a way which is more in line with what the user would expect. Sharp boundaries are visualized where the certainty is high while uncertain areas are visualized with fuzzy boundaries. The volume exploration process of mapping data values to optical properties through the transfer function has traditionally been complex and performed by expert users. A study at a science center showed that visitors favor the presented dynamic gallery method compared to the most commonly used transfer function editor.

    List of papers
    1. A Survey of Volumetric Illumination Techniques for Interactive Volume Rendering
    Open this publication in new window or tab >>A Survey of Volumetric Illumination Techniques for Interactive Volume Rendering
    2014 (English)In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 33, no 1, 27-51 p.Article in journal (Refereed) Published
    Abstract [en]

    Interactive volume rendering in its standard formulation has become an increasingly important tool in many application domains. In recent years several advanced volumetric illumination techniques to be used in interactive scenarios have been proposed. These techniques claim to have perceptual benefits as well as being capable of producing more realistic volume rendered images. Naturally, they cover a wide spectrum of illumination effects, including varying shading and scattering effects. In this survey, we review and classify the existing techniques for advanced volumetric illumination. The classification will be conducted based on their technical realization, their performance behaviour as well as their perceptual capabilities. Based on the limitations revealed in this review, we will define future challenges in the area of interactive advanced volumetric illumination.

    Place, publisher, year, edition, pages
    Wiley, 2014
    Keyword
    volume rendering; rendering; volume visualization; visualization; illumination rendering; rendering
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-105757 (URN)10.1111/cgf.12252 (DOI)000331694100004 ()
    Available from: 2014-04-07 Created: 2014-04-04 Last updated: 2017-12-05
    2. Efficient Visibility Encoding for Dynamic Illumination in Direct Volume Rendering: -
    Open this publication in new window or tab >>Efficient Visibility Encoding for Dynamic Illumination in Direct Volume Rendering: -
    Show others...
    2012 (English)In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 18, no 3, 447-462 p.Article in journal (Refereed) Published
    Abstract [sv]

    We present an algorithm that enables real-time dynamic shading in direct volume rendering using general lighting, includingdirectional lights, point lights and environment maps. real-time performance is achieved by encoding local and global volumetricvisibility using spherical harmonic (SH) basis functions stored in an efficient multi-resolution grid over the extent of the volume. Ourmethod enables high frequency shadows in the spatial domain, but is limited to a low frequency approximation of visibility and illuminationin the angular domain. In a first pass, Level Of Detail (LOD) selection in the grid is based on the current transfer function setting.This enables rapid on-line computation and SH projection of the local spherical distribution of visibility information. Using a piecewiseintegration of the SH coefficients over the local regions, the global visibility within the volume is then computed. By representing thelight sources using their SH projections, the integral over lighting, visibility and isotropic phase functions can be efficiently computedduring rendering. The utility of our method is demonstrated in several examples showing the generality and interactive performanceof the approach.

    Place, publisher, year, edition, pages
    IEEE, 2012
    Keyword
    Volumetric Illumination, Precomputed Radiance Transfer, Volume Rendering
    National Category
    Other Computer and Information Science
    Identifiers
    urn:nbn:se:liu:diva-66839 (URN)10.1109/TVCG.2011.35 (DOI)000299281700010 ()
    Projects
    CADICSMOVIII
    Note
    ©2011 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Joel Kronander, Daniel Jönsson, Joakim Löw, Patric Ljung, Anders Ynnerman and Jonas Unger, Efficient Visibility Encoding for Dynamic Illumination in Direct Volume Rendering, 2011, IEEE Transactions on Visualization and Computer Graphics. http://dx.doi.org/10.1109/TVCG.2011.35 Available from: 2011-03-24 Created: 2011-03-21 Last updated: 2018-01-12Bibliographically approved
    3. Historygrams: Enabling Interactive Global Illumination in Direct Volume Rendering using Photon Mapping
    Open this publication in new window or tab >>Historygrams: Enabling Interactive Global Illumination in Direct Volume Rendering using Photon Mapping
    2012 (English)In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 18, no 12, 2364-2371 p.Article in journal (Refereed) Published
    Abstract [en]

    In this paper, we enable interactive volumetric global illumination by extending photon mapping techniques to handle interactive transfer function (TF) and material editing in the context of volume rendering. We propose novel algorithms and data structures for finding and evaluating parts of a scene affected by these parameter changes, and thus support efficient updates of the photon map. In direct volume rendering (DVR) the ability to explore volume data using parameter changes, such as editable TFs, is of key importance. Advanced global illumination techniques are in most cases computationally too expensive, as they prevent the desired interactivity. Our technique decreases the amount of computation caused by parameter changes, by introducing Historygrams which allow us to efficiently reuse previously computed photon media interactions. Along the viewing rays, we utilize properties of the light transport equations to subdivide a view-ray into segments and independently update them when invalid. Unlike segments of a view-ray, photon scattering events within the volumetric medium needs to be sequentially updated. Using our Historygram approach, we can identify the first invalid photon interaction caused by a property change, and thus reuse all valid photon interactions. Combining these two novel concepts, supports interactive editing of parameters when using volumetric photon mapping in the context of DVR. As a consequence, we can handle arbitrarily shaped and positioned light sources, arbitrary phase functions, bidirectional reflectance distribution functions and multiple scattering which has previously not been possible in interactive DVR.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2012
    Keyword
    Volume rendering, photon mapping, global illumination, participating media
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86634 (URN)10.1109/TVCG.2012.232 (DOI)000310143100040 ()
    Projects
    CADICSCMIV
    Note

    Funding Agencies|Excellence Center at Linkoping and Lund in Information Technology (ELLIIT)||Swedish e-Science Research Centre (SeRC)||

    Available from: 2012-12-20 Created: 2012-12-20 Last updated: 2017-12-06
    4. Correlated Photon Mapping for Interactive Global Illumination of Time-Varying Volumetric Data
    Open this publication in new window or tab >>Correlated Photon Mapping for Interactive Global Illumination of Time-Varying Volumetric Data
    2017 (English)In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 23, no 1, 901-910 p.Article in journal (Refereed) Published
    Abstract [en]

    We present a method for interactive global illumination of both static and time-varying volumetric data based on reduction of the overhead associated with re-computation of photon maps. Our method uses the identification of photon traces invariant to changes of visual parameters such as the transfer function (TF), or data changes between time-steps in a 4D volume. This lets us operate on a variant subset of the entire photon distribution. The amount of computation required in the two stages of the photon mapping process, namely tracing and gathering, can thus be reduced to the subset that are affected by a data or visual parameter change. We rely on two different types of information from the original data to identify the regions that have changed. A low resolution uniform grid containing the minimum and maximum data values of the original data is derived for each time step. Similarly, for two consecutive time-steps, a low resolution grid containing the difference between the overlapping data is used. We show that this compact metadata can be combined with the transfer function to identify the regions that have changed. Each photon traverses the low-resolution grid to identify if it can be directly transferred to the next photon distribution state or if it needs to be recomputed. An efficient representation of the photon distribution is presented leading to an order of magnitude improved performance of the raycasting step. The utility of the method is demonstrated in several examples that show visual fidelity, as well as performance. The examples show that visual quality can be retained when the fraction of retraced photons is as low as 40%-50%.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2017
    Keyword
    Volume rendering, photon mapping, global illumination, participating media
    National Category
    Media Engineering
    Identifiers
    urn:nbn:se:liu:diva-131022 (URN)10.1109/TVCG.2016.2598430 (DOI)000395537600093 ()27514045 (PubMedID)2-s2.0-84999158356 (Scopus ID)
    Projects
    SERCCMIV
    Note

    Funding Agencies|Swedish e-Science Research Centre (SeRC)||Swedish Research Council (VR) grant 2016-05462||Knut and Alice Wallenberg Foundation (KAW) grant 2016-0076||

    Available from: 2016-09-05 Created: 2016-09-05 Last updated: 2017-04-20Bibliographically approved
    5. Boundary Aware Reconstruction of Scalar Fields
    Open this publication in new window or tab >>Boundary Aware Reconstruction of Scalar Fields
    2014 (English)In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 20, no 12, 2447-2455 p.Article in journal (Refereed) Published
    Abstract [en]

    In visualization, the combined role of data reconstruction and its classification plays a crucial role. In this paper we propose a novel approach that improves classification of different materials and their boundaries by combining information from the classifiers at the reconstruction stage. Our approach estimates the targeted materials’ local support before performing multiple material-specific reconstructions that prevent much of the misclassification traditionally associated with transitional regions and transfer function (TF) design. With respect to previously published methods our approach offers a number of improvements and advantages. For one, it does not rely on TFs acting on derivative expressions, therefore it is less sensitive to noisy data and the classification of a single material does not depend on specialized TF widgets or specifying regions in a multidimensional TF. Additionally, improved classification is attained without increasing TF dimensionality, which promotes scalability to multivariate data. These aspects are also key in maintaining low interaction complexity. The results are simple-to-achieve visualizations that better comply with the user’s understanding of discrete features within the studied object.

    Place, publisher, year, edition, pages
    IEEE Press, 2014
    National Category
    Computer and Information Sciences Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-110227 (URN)10.1109/TVCG.2014.2346351 (DOI)000344991700090 ()
    Available from: 2014-09-04 Created: 2014-09-04 Last updated: 2018-01-11Bibliographically approved
    6. Intuitive Exploration of Volumetric Data Using Dynamic Galleries
    Open this publication in new window or tab >>Intuitive Exploration of Volumetric Data Using Dynamic Galleries
    2016 (English)In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 22, no 1, 896-905 p.Article in journal (Refereed) Published
    Abstract [en]

    In this work we present a volume exploration method designed to be used by novice users and visitors to science centers and museums. The volumetric digitalization of artifacts in museums is of rapidly increasing interest as enhanced user experience through interactive data visualization can be achieved. This is, however, a challenging task since the vast majority of visitors are not familiar with the concepts commonly used in data exploration, such as mapping of visual properties from values in the data domain using transfer functions. Interacting in the data domain is an effective way to filter away undesired information but it is difficult to predict where the values lie in the spatial domain. In this work we make extensive use of dynamic previews instantly generated as the user explores the data domain. The previews allow the user to predict what effect changes in the data domain will have on the rendered image without being aware that visual parameters are set in the data domain. Each preview represents a subrange of the data domain where overview and details are given on demand through zooming and panning. The method has been designed with touch interfaces as the target platform for interaction. We provide a qualitative evaluation performed with visitors to a science center to show the utility of the approach.

    Place, publisher, year, edition, pages
    IEEE COMPUTER SOC, 2016
    Keyword
    Transfer function; scalar fields; volume rendering; touch interaction; visualization; user interfaces
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-123054 (URN)10.1109/TVCG.2015.2467294 (DOI)000364043400095 ()26390481 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council, VR [2011-5816]; Excellence Center at Linkoping and Lund in Information Technology (ELLIIT); Linnaeus Environment CADICS; Swedish e-Science Research Centre (SeRC)

    Available from: 2015-12-04 Created: 2015-12-03 Last updated: 2017-12-01
  • 49.
    Karlsson, Anders
    et al.
    Linköping University, Department of Electrical Engineering.
    Bjärkefur, Jon
    Linköping University, Department of Computer and Information Science.
    Simultaneous Localisation and Mapping of Indoor Environments Using a Stereo Camera and a Laser Camera2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis describes and investigates different approaches to indoor mapping and navigation. A system capable of mapping large indoor areas with a stereo camera and/or a laser camera mounted to e.g. a robot or a human is developed. The approaches investigated in this report are either based on Simultaneous Lo- calisation and Mapping (SLAM) techniques, e.g. Extended Kalman Filter-SLAM (EKF-SLAM) and Smoothing and Mapping (SAM), or registration techniques, e.g. Iterated Closest Point (ICP) and Normal Distributions Transform (NDT).In SLAM, it is demonstrated that the laser camera can contribute to the stereo camera by providing accurate distance estimates. By combining these sensors in EKF-SLAM, it is possible to obtain more accurate maps and trajectories compared to if the stereo camera is used alone.It is also demonstrated that by dividing the environment into smaller ones, i.e. submaps, it is possible to build large maps in close to linear time. A new approach to SLAM based on EKF-SLAM and SAM, called Submap Joining Smoothing and Mapping (SJSAM), is implemented to demonstrate this.NDT is also implemented and the objective is to register two point clouds from the laser camera to each other so that the relative motion can be obtained. The NDT implementation is compared to ICP and the results show that NDT performs better at estimating the angular difference between the point clouds.

  • 50.
    Karlsson, Jonathan
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Using WebGL to create TV-centric user interfaces2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    In recent years the user interfaces of the TV platform have been powered by HTML, but since the platform is starting to support new techniques it might be time to change the focus. HTML is a good choice for interface development because of its high level and platform independence; however, when performance is critical and the requirements are high HTML can impose serious restrictions. WebGL is a technology released in 2011 that brings a low-level graphics API to the web. The API allows for development of advanced 3D graphics and visual effects that were impossible or impractical in the HTML world. The problem is that the hassle of using pure WebGL is in most cases too big to overcome. In this thesis a proof-of-concept was developed to investigate the issues and limitations of WebGL. A conclusion was made that even though the performance was not as good as expected it might still be viable for use in some settings.

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