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  • 1001.
    Valter, Andreas
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Dynamic real-time scene voxelization and an application for large scale scenes2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This report describes a basic implementation of scene voxelization within the Frostbite engine created by EA Frostbite. The algorithm supports dynamic scenes by voxelizing in real-time using the Graphical Programming Unit. The voxel grid is stored inside a buffer with a binary representation using clip mapping and multiple levels of detail. An ambient occlusion algorithm is implemented to show the benefits of the structure. Results from running the application within the engine is presented, both with figures showing the resulting image and timings for diifferent parts of the algorithm. Several future improvements to make the algorithm more competitive is presented as well.

    Fulltekst (pdf)
    fulltext
  • 1002.
    van Leeuwen, Ellinor
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Posterdesign: att förmedla ett budskap genom färg och typografi2019Independent thesis Basic level (university diploma), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    There are people that uses notes to motivate themselves or to remind themselves of things or situations. These notes, these messages, seems to be very meaningful for these people because the notes are placed in some of the most visible places, in their homes or at work, to been seen in a daily basis. Due to this value, the message deserves a better visual presentation, through an interior detail, a poster. The purpose of this study was to bring the right feeling within the message throughout a poster with  color and typography.

    As a start, theory was collected with focus on color and typography. This followed by a pre-study where a questionnaire was handed out to the public to collect the notes. A research was made to investigate todays trends in poster design to get an understanding of the looks of the trends and connect it with different types of habits and usage of color and typography.

    The design process started with a design analysis where the theory was put in relation to the messages. Out of this, some sketches were made that later was evaluated and gave the result of 2-4 drafts per message, 24 drafts in total. These drafts were later evaluated by interviews together with participants within and outside the field of graphic design. After the evaluation a compilation was made and another analysis was made and this led to nine finalized posters, one for each message.

    The conclusion presents the finalized posters that were made based on theories and interviews. It also shows that there were several parameters that affected each other. The message affected the design and the design affected the message which in turn also got affected by the interview participants individual relations and feelings towards the message and the design.

    Fulltekst (pdf)
    Posterdesign: att förmedla ett budskap genom färg och typografi
  • 1003.
    Vennström, Anders
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Per-Erik
    Luleå tekniska universitet.
    Exploitation Of Exploratory Knowledge: A Multiple Case Study of Knowledge Diffusion From Demonstration Projects2013Inngår i: 7th Nordic Conference on Construction Economics and Organisations: Green Urbanisation - Implications for value creation / [ed] Ole Jonny Klakegg, Trondheim: Akademika forlag, 2013, s. 335-345Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Previous research in various industrial contexts has shown that companies needs to achieve both exploitation of current knowledge, and exploration of new knowledge to be successful in changing conditions. In the construction sector exploration activities are sometimes conducted in demonstration projects. The project based nature of the sector is, however, argued to be one common obstacle to exploitation and diffusion of knowledge and innovation. In Sweden, the government has financed different demonstration projects, through The National Board of Housing, Building and Planning, in order to facilitate development and diffusion of new knowledge. This paper sets out to compile the results of a previous study of  conducted demonstration projects and establish a framework and research questions for a follow up study of the demonstration projects six years after their completion in order to assess the extent of knowledge diffusion. The previous study is based on interviews with the clients’ project managers and document studies of reports published from the demonstration projects. The tentative findings show that the projects involved product, process, organizational/contractual and financial/revenue innovations. The result also shows that the investigated projects were reported as successful and therefore could serve as base for diffusion of new knowledge. In the second step the study will investigate if and how knowledge was diffused from the demonstration projects among the involved actors.

  • 1004.
    Vistisen, Peter
    et al.
    Institut for Kommunikation og Psykologi, Det Humanistiske Fakultet, InDiMedia (Center for Interaktive Digitale Medier & Oplevelsesdesign), Aalborg University, Denmark.
    Tran Luciani, Danwei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ekströmer, Philip
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Sketching Immersive Information Spaces: Lessons learned from experiments in '˜sketching for and through virtual reality'2019Inngår i: Proceedings of the 7th eCAADe Regional International Symposium, eCAADe , 2019, Vol. 7, s. 147-157Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the lessons learned from a design workshop exploring methods for early exploration of immersive information spaces, such as Virtual Reality (VR). The methods explored cover design situations both designing for VR, and designing through VR, in varying degrees of fidelity. The workshops shared the common factor of attempting to enable a feedback loop between sketching activities and the more didactic and time consuming prototyping processes. From our analysis, we found that to achieve true ‘sketchiness’ in an immersive VR settings, tool proficiency naturally becomes a decisive factor, since a lot of new techniques needs to be learned and gained experience with. Furthermore, it is evident that the mental shift, from flat to 360 degree design, was challenging, but also the enabler of new creative constraints from which the designer can explore the boundaries of the design space. We conclude by arguing for the development of more formalized patterns, materials and tools to not just enable immersive sketching, but also enable grasping the immersive design space itself by motivating the explorations and happy accidents when ‘doodling’ in the immersive space.

    Fulltekst (pdf)
    Sketching Immersive Information Spaces: Lessons learned from experiments in '˜sketching for and through virtual reality'
  • 1005. Bestill onlineKjøp publikasjonen >>
    Vitória, Aida
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik.
    Reasoning with Rough Sets and Paraconsistent Rough Sets2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents an approach to knowledge representation combining rough sets and para-consistent logic programming.

    The rough sets framework proposes a method to handle a specific type of uncertainty originating from the fact that an agent may perceive different objects of the universe as being similar, although they may have di®erent properties. A rough set is then defined by approximations taking into account the similarity between objects. The number of applications and the clear mathematical foundation of rough sets techniques demonstrate their importance.

    Most of the research in the rough sets field overlooks three important aspects. Firstly, there are no established techniques for defining rough concepts (sets) in terms of other rough concepts and for reasoning about them. Secondly, there are no systematic methods for integration of domain and expert knowledge into the definition of rough concepts. Thirdly, some additional forms of uncertainty are not considered: it is assumed that knowledge about similarities between objects is precise, while in reality it may be incomplete and contradictory; and, for some objects there may be no evidence about whether they belong to a certain concept.

    The thesis addresses these problems using the ideas of paraconsistent logic programming, a recognized technique which makes it possible to represent inconsistent knowledge and to reason about it. This work consists of two parts, each of which proposes a di®erent language. Both languages cater for the definition of rough sets by combining lower and upper approximations and boundaries of other rough sets. Both frameworks take into account that membership of an object into a concept may be unknown.

    The fundamental difference between the languages is in the treatment of similarity relations. The first language assumes that similarities between objects are represented by equivalence relations induced from objects with similar descriptions in terms of a given number of attributes. The second language allows the user to define similarity relations suitable for the application in mind and takes into account that similarity between objects may be imprecise. Thus, four-valued similarity relations are used to model indiscernibility between objects, which give rise to rough sets with four-valued approximations, called paraconsistent rough sets. The semantics of both languages borrows ideas and techniques used in paraconsistent logic programming. Therefore, a distinctive feature of our work is that it brings together two major fields, rough sets and paraconsistent logic programming.

    Delarbeid
    1. A framework for reasoning with rough sets
    Åpne denne publikasjonen i ny fane eller vindu >>A framework for reasoning with rough sets
    2005 (engelsk)Inngår i: Transactions on Rough Sets IV / [ed] James F. Peters and Andrzej Skowron, Springer Berlin/Heidelberg, 2005, Vol. 3700, s. 178-276Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Rough sets framework has two appealing aspects. First, it is a mathematical approach to deal with vague concepts. Second, rough set techniques can be used in data analysis to find patterns hidden in the data. The number of applications of rough sets to practical problems in different fields demonstrates the increasing interest in this framework and its applicability. This thesis(1) proposes a language that caters for implicit definitions of rough sets obtained by combining different regions of other rough sets. In this way, concept approximations can be derived by taking into account domain knowledge. A declarative semantics for the language is also discussed. It is then shown that programs in the proposed language can be compiled to extended logic programs under the paraconsistent stable model semantics. The equivalence between the declarative semantics of the language and the declarative semantics of the compiled programs is proved. This transformation provides the computational basis for implementing our ideas. A query language for retrieving information about the concepts represented through the defined rough sets is also discussed. Several motivating applications are described. Finally, an extension of the proposed language with numerical measures is presented. This extension is motivated by the fact that numerical measures are an important aspect in data mining applications.

    sted, utgiver, år, opplag, sider
    Springer Berlin/Heidelberg, 2005
    Serie
    Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 3700
    Serie
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 3700
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-48115 (URN)10.1007/11574798_10 (DOI)978-3-540-29830-4 (ISBN)978-3-540-32016-6 (ISBN)3-540-29830-4 (ISBN)
    Tilgjengelig fra: 2009-10-11 Laget: 2009-10-11 Sist oppdatert: 2018-02-15bibliografisk kontrollert
    2. Modelling and Reasoning with Paraconsistent Rough Sets
    Åpne denne publikasjonen i ny fane eller vindu >>Modelling and Reasoning with Paraconsistent Rough Sets
    2009 (engelsk)Inngår i: Fundamenta Informaticae, ISSN 0169-2968, E-ISSN 1875-8681, Vol. 97, nr 4, s. 405-438Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We present a language for defining paraconsistent rough sets and reasoning about them. Our framework relates and brings together two major fields: rough sets [23] and paraconsistent logic programming [9]. To model inconsistent and incomplete information we use a four-valued logic. The language discussed in this paper is based on ideas of our previous work [21, 32, 22] developing a four-valued framework for rough sets. In this approach membership function, set containment and set operations are four-valued, where logical values are t (true), f (false), i (inconsistent) and u (unknown). We investigate properties of paraconsistent rough sets as well as develop a paraconsistent rule language, providing basic computational machinery for our approach.

    Emneord
    approximate reasoning, rough sets, paraconsistent reasoning, four-valued logics
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-53059 (URN)10.3233/FI-2009-209 (DOI)
    Tilgjengelig fra: 2010-01-15 Laget: 2010-01-15 Sist oppdatert: 2017-12-12
    Fulltekst (pdf)
    Reasoning with Rough Sets and Paraconsistent Rough Sets
    Download (pdf)
    omslag
  • 1006.
    Volpi, Riccardo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Kottravel, Sathish
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Norby, Morten Sten
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Denmark.
    Stafström, Sven
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Linares, Mathieu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Effect of Polarization on the Mobility of C60: A Kinetic Monte-Carlo Study2016Inngår i: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 12, nr 2, s. 812-824Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a study of mobility field and temperature dependence for C60 with Kinetic Monte-Carlo simulations. We propose a new scheme to take into account polarization effects in organic materials through atomic induced dipoles on nearby molecules. This leads to an energy correction for the single site energies and to an external reorganization happening after each hopping. The inclusion of polarization allows us to obtain a good agreement with experiments for both mobility field and temperature dependence.

  • 1007.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Andersson, Gunnel
    FoU Sodertorn, Sweden; Stockholm Univ, Sweden.
    Ellegård, Kajsa
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    Stefansson, Claes-Göran
    Stockholm Univ, Sweden.
    Topor, Alain
    Stockholm Univ, Sweden; Univ Agder, Norway.
    Denhov, Anne
    Stockholm Univ, Sweden.
    Bulow, Per
    Jonkoping Univ, Sweden.
    A time-geographic approach for visualizing the paths of intervention for persons with severe mental illness2017Inngår i: Geografiska Annaler. Series B, Human Geography, ISSN 0435-3684, E-ISSN 1468-0467, Vol. 99, nr 4, s. 341-359Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Living conditions for persons with severe mental illness (SMI) in Sweden have changed dramatically in recent decades, mainly due to the closure of mental hospitals in the 1990s and the subsequent development of community-based interventions. Thereby, people with SMI have experienced care interventions in various forms, which vary according to how the treatment is institutionally organised over the years. There is, however, a lack of knowledge concerning what "care paths" persons with SMI have undergone in this fragmented institutional landscape. In this article we present a time-geography-inspired visualisation method to address this. A set of 437 persons, first diagnosed with psychosis between 2000-2004, were studied over 10 years with regard to their contact with various care institutions. We constructed time-geographic paths of intervention for these individuals and visualised them at an aggregate level. The initial exploration conducted using the proposed visualisation method showed gender and age differences in some respects, but also that the initial periods after the psychosis diagnoses were similar in terms of in-patient care interventions among men and women. The proposed visualisation method is promising and should be further developed for deeper analysis of long-term individual paths of intervention.

  • 1008.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Andrienko, Gennady
    University of Bonn and Fraunhofer Institute IAIS, Germany.
    Andrienko, Natalia
    University of Bonn and Fraunhofer Institute IAIS, Germany.
    Interactive visual analysis of event-based movement data extracted from phone call records2012Inngår i: Geoinformationssysteme: Beiträge zum 17. Münchner Fortbildungsseminar 2012 / [ed] Koch, Kutzner, Eder, Munich, Germany: Wichmann , 2012Konferansepaper (Annet vitenskapelig)
  • 1009.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Bergqvist, Mathias
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Cooper, Matthew
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ellegård, Kajsa
    Linköpings universitet, Institutionen för tema, Tema teknik och social förändring. Linköpings universitet, Filosofiska fakulteten.
    PODD: A Portable Diary Data Collection System2014Inngår i: AVI '14 Proceedings of the 2014 International Working Conference on Advanced Visual Interfaces, New York: Association for Computing Machinery (ACM), 2014, s. 381-382Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Activity diaries are a powerful data source for studying the time use of individuals and for creating awareness of individuals' daily activity patterns. The presented project is concerned with the development of an easily accessible method for collecting and analyzing diary data which will be applicable across a wide range of industrial, governmental, social science and medical domains. The PODD (POrtable Diary Data collection) is composed of a smartphone application for data registration, a web interface for user registration and an administration system for configuring the application according to the focus of the data collection.

  • 1010.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Forsell, Camilla
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    A Qualitative Study of Similarity Measures in Event-Based Data2011Inngår i: Human Interface and the Management of Information. Interacting with Information: Symposium on Human Interface 2011, Held as Part of HCI International 2011, Orlando, FL, USA, July 9-14, 2011, Proceedings, Part I / [ed] Michael J. Smith and Gavriel Salvendy, Berlin/Heidelberg: Springer, 2011, s. 170-179Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This paper presents an interview-based study of the definition of sequence similarity in different application areas of event-based data. The applicability of nine identified measures across these areas is investigated and discussed. The work helps highlight what are the core characteristics sought when analysing event-based data and performs a first validation of this across disciplines. The results of the study make a solid basis for follow-up evaluations of the practical applicability and usability of the similarity measures.

  • 1011.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Fuchs, Georg
    Fraunhofer Institute IAIS, Sankt-Augustin, Germany.
    Andrienko, Natalia
    Fraunhofer Institute IAIS, Sankt-Augustin, Germany; City University London, London, UK.
    Andrienko, Gennady
    Fraunhofer Institute IAIS, Sankt-Augustin, Germany; City University London, London, UK.
    An Interactive Approach for Exploration of Flows Through Direction-Based Filtering2017Inngår i: Journal of Geovisualization and Spatial Analysis, ISSN 2509-8810, Vol. 1, nr 1-2, artikkel-id 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper is concerned with the representation and exploration of flows, defined as spatial interactions between geographic locations. Flows are challenging to display in a comprehensible manner due to the nature of the data, which are characterized by many crossings and overlaps leading to clutter. A number of different strategies have been suggested for addressing this problem, which commonly involve reducing the search space, aggregating the data or simplifying the representations often at the cost of information loss or distortion of spatial context. We propose an interactive approach for exploring large and highly connected networks of flows without distorting the geographical space and without losing the context overview in the process. The approach is based on a flow-specific interaction technique for filtering the data by direction, that enables an analyst to successively identify underlying spatial arrangement patterns. We illustrate our approach through exploring flows of tourists and locals in the Greater London area.

    Fulltekst (pdf)
    fulltext
  • 1012.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Janetzko, Halldor
    University of Konstanz, Germany.
    Navarra, Carlo
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Fuchs, Georg
    University of Bonn, Germany.
    Spretke, David
    University of Konstanz, Germany.
    Mansmann, Florian
    University of Konstanz, Germany.
    Andrienko, Natalia
    University of Bonn, Germany.
    Andrienko, Gennady
    University of Bonn, Germany.
    SimpliFly: A Methodology for Simplification and Thematic Enhancement of Trajectories2015Inngår i: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 21, nr 1, s. 107-121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Movement data sets collected using todays advanced tracking devices consist of complex trajectories in terms of length, shape, and number of recorded positions. Multiple additional attributes characterizing the movement and its environment are often also included making the level of complexity even higher. Simplification of trajectories can improve the visibility of relevant information by reducing less relevant details while maintaining important movement patterns. We propose a systematic stepwise methodology for simplifying and thematically enhancing trajectories in order to support their visual analysis. The methodology is applied iteratively and is composed of: (a) a simplification step applied to reduce the morphological complexity of the trajectories, (b) a thematic enhancement step which aims at accentuating patterns of movement, and (c) the representation and interactive exploration of the results in order to make interpretations of the findings and further refinement to the simplification and enhancement process. We illustrate our methodology through an analysis example of two different types of tracks, aircraft and pedestrian movement.

    Fulltekst (pdf)
    fulltext
  • 1013.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Nordman, Aida
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Exploratory visual sequence mining based on pattern-growth2019Inngår i: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 25, nr 8, s. 2597-2610Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sequential pattern mining finds applications in numerous diverging fields. Due to the problem's combinatorial nature, two main challenges arise. First, existing algorithms output large numbers of patterns many of which are uninteresting from a user's perspective. Second, as datasets grow, mining large number of patterns gets computationally expensive. There is, thus, a need for mining approaches that make it possible to focus the pattern search towards directions of interest. This work tackles this problem by combining interactive visualization with sequential pattern mining in order to create a "transparent box" execution model. We propose a novel approach to interactive visual sequence mining that allows the user to guide the execution of a pattern-growth algorithm at suitable points through a powerful visual interface. Our approach (1) introduces the possibility of using local constraints during the mining process, (2) allows stepwise visualization of patterns being mined, and (3) enables the user to steer the mining algorithm towards directions of interest. The use of local constraints significantly improves users' capability to progressively refine the search space without the need to restart computations. We exemplify our approach using two event sequence datasets; one composed of web page visits and another composed of individuals' activity sequences.

  • 1014.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Vitoria, Aida
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Interactive Visual Sequence Mining Based on Pattern-Growth2014Inngår i: IEEE Conference on Visual Analytics Science and Technology (VAST), Institute of Electrical and Electronics Engineers (IEEE), 2014, s. 285-286Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Sequential pattern mining aims to discover valuable patterns from datasets and has a vast number of applications in various fields. Due to the combinatorial nature of the problem, the existing algorithms tend to output long lists of patterns that often suffer from a lack offocus from the user perspective. Our aim is to tackle this problemby combining interactive visualization techniques with sequential pattern mining to create a “transparent box” execution model for existing algorithms. This paper describes our first step in this direction and gives an overview of a system that allows the user to guide the execution of a pattern-growth algorithm at suitable points, through a powerful visual interface.

  • 1015.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ynnerman, Anders
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Cooper, Matthew
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Are we what we do? Exploring group behaviour through user-defined event-sequence similarity2014Inngår i: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 13, nr 3, s. 232-247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study of human activity in space and time is an inherent part of human geography. In order to perform such studies, data on the time use of individuals, in terms of sequence and timing of performed activities, are collected and analysed. A common assumption when analysing individuals’ time use is that groups that exhibit similar background and demographic characteristics also display similarities in how they use their time to structure their daily lives. In this article, we set out to investigate the correctness of such assumptions. We propose a visual analytics process based on sequence similarity measures tailored to event-based data such as performed activity sequences. The process allows an analyst to retrieve similarly behaving records according to user-selected similarity preferences and interactively explore aspects of this similarity in a multiple linked-view environment.

    Fulltekst (pdf)
    fulltext
  • 1016.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Zhi, Haolin
    Fraunhofer IAIS, Sankt Augustin, Germany.
    Peca, Iulian
    Fraunhofer IAIS, Sankt Augustin, Germany.
    Andrienko, Gennady
    Fraunhofer IAIS, Sankt Augustin, Germany.
    Andrienko, Natalia
    Fraunhofer IAIS, Sankt Augustin, Germany.
    Interactive Exploration of Events and Presence of People in Space and Time through KD-Photomap2012Inngår i: AVI '12 Proceedings of the International Working Conference on Advanced Visual Interfaces / [ed] Negulescu M.; Ruiz J.; Lank E.; Li Y., ACM Press, 2012, s. 804-805Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We explore people's activities in space and time by analysing publicly available georefenced photographs. We do this using KD-photomap, a web-based visual analytics system for exploring collections of Flickr photographs and meta-data associated with them. The system provides an interface for flexible browsing of photographs in search of interesting pictures, and places, and also a framework for exploration of presence and identification of events in space and time.

  • 1017.
    Wang, Chunliang
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. KTH Royal Institute Technology, Sweden; Sectra AB, S-58330 Linkoping, Sweden.
    Dahlström, Nils
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Röntgenkliniken i Linköping. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Fransson, Sven Göran
    Region Östergötland, Diagnostikcentrum, Röntgenkliniken i Linköping. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper.
    Lundström, Claes
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Smedby, Örjan
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Röntgenkliniken i Linköping. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. KTH Royal Institute Technology, Sweden.
    Real-Time Interactive 3D Tumor Segmentation Using a Fast Level-Set Algorithm2015Inngår i: Journal of Medical Imaging and Health Informatics, ISSN 2156-7018, E-ISSN 2156-7026, Vol. 5, nr 8, s. 1998-2002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new level-set based interactive segmentation framework is introduced, where the algorithm learns the intensity distributions of the tumor and surrounding tissue from a line segment drawn by the user from the middle of the lesion towards the border. This information is used to design a likelihood function, which is then incorporated into the level-set framework as an external speed function guiding the segmentation. The endpoint of the input line segment sets a limit to the propagation of 3D region, i.e., when the zero-level-set crosses this point, the propagation is forced to stop. Finally, a fast level set algorithm with coherent propagation is used to solve the level set equation in real time. This allows the user to instantly see the 3D result while adjusting the position of the line segment to tune the parameters implicitly. The "fluctuating" character of the coherent propagation also enables the contour to coherently follow the mouse cursors motion when the user tries to fine-tune the position of the contour on the boundary, where the learned likelihood function may not necessarily change much. Preliminary results suggest that radiologists can easily learn how to use the proposed segmentation tool and perform relatively accurate segmentation with much less time than the conventional slice-by-slice based manual procedure.

  • 1018.
    Wang, Chunliang
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Sectra, Linkoping, Sweden.
    Forsberg, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Sectra, Linkoping, Sweden.
    Segmentation of Intervertebral Discs in 3D MRI Data Using Multi-atlas Based Registration2016Inngår i: Computational Methods and Clinical Applications for Spine Imaging, CSI 2015, SPRINGER INT PUBLISHING AG , 2016, Vol. 9402, s. 107-116Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents one of the participating methods to the intervertebral disc segmentation challenge organized in conjunction with the 3rd MICCAI Workshop amp; Challenge on Computational Methods and Clinical Applications for Spine Imaging - MICCAI-CSI2015. The presented method consist of three steps. In the first step, vertebral bodies are detected and labeled using integral channel features and a graphical parts model. The second step consists of image registration, where a set of image volumes with corresponding intervertebral disc atlases are registered to the target volume using the output from the first step as initialization. In the final step, the registered atlases are combined using label fusion to derive the final segmentation. The pipeline was evaluated using a set of 15 + 10 T2-weighted image volumes provided as training and test data respectively for the segmentation challenge. For the training data, a mean disc centroid distance of 0.86 mm and an average DICE score of 91% was achieved, and for the test data the corresponding results were 0.90 mm and 90%.

  • 1019.
    Wang, Chunliang
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Sectra AB, Linköping, Sweden; School of Technology and Health, Royal Institute of Technology - KTH, Stockholm, Sweden.
    Lundström, Claes
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Sectra AB, Linköping, Sweden.
    CT scan range estimation using multiple body parts detection: let PACS learn the CT image content2016Inngår i: International Journal of Computer Assisted Radiology and Surgery, ISSN 1861-6410, E-ISSN 1861-6429, Vol. 39, nr 2, s. 149-159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose

    The aim of this study was to develop an efficient CT scan range estimation method that is based on the analysis of image data itself instead of metadata analysis. This makes it possible to quantitatively compare the scan range of two studies.

    Methods

    In our study, 3D stacks are first projected to 2D coronal images via a ray casting-like process. Trained 2D body part classifiers are then used to recognize different body parts in the projected image. The detected candidate regions go into a structure grouping process to eliminate false-positive detections. Finally, the scale and position of the patient relative to the projected figure are estimated based on the detected body parts via a structural voting. The start and end lines of the CT scan are projected to a standard human figure. The position readout is normalized so that the bottom of the feet represents 0.0, and the top of the head is 1.0.

    Results

    Classifiers for 18 body parts were trained using 184 CT scans. The final application was tested on 136 randomly selected heterogeneous CT scans. Ground truth was generated by asking two human observers to mark the start and end positions of each scan on the standard human figure. When compared with the human observers, the mean absolute error of the proposed method is 1.2 % (max: 3.5 %) and 1.6 % (max: 5.4 %) for the start and end positions, respectively.

    Conclusion

    We proposed a scan range estimation method using multiple body parts detection and relative structure position analysis. In our preliminary tests, the proposed method delivered promising results.

  • 1020.
    Wang, Xiyao
    et al.
    INRIA, France; Univ Paris Saclay, France.
    Besancon, Lonni
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ammi, Mehdi
    Univ Paris 08, France.
    Isenberg, Tobias
    INRIA, France.
    Augmenting Tactile 3D Data Navigation With Pressure Sensing2019Inngår i: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 38, nr 3, s. 635-647Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a pressure-augmented tactile 3D data navigation technique, specifically designed for small devices, motivated by the need to support the interactive visualization beyond traditional workstations. While touch input has been studied extensively on large screens, current techniques do not scale to small and portable devices. We use phone-based pressure sensing with a binary mapping to separate interaction degrees of freedom (DOF) and thus allow users to easily select different manipulation schemes (e. g., users first perform only rotation and then with a simple pressure input to switch to translation). We compare our technique to traditional 3D-RST (rotation, scaling, translation) using a docking task in a controlled experiment. The results show that our technique increases the accuracy of interaction, with limited impact on speed. We discuss the implications for 3D interaction design and verify that our results extend to older devices with pseudo pressure and are valid in realistic phone usage scenarios.

  • 1021.
    Warwick, J.
    et al.
    Queens University of Belfast, North Ireland.
    Dzelzainis, T.
    Queens University of Belfast, North Ireland.
    Dieckmann, Mark E
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Schumaker, W.
    SLAC National Accelerator Lab, CA 94025 USA.
    Doria, D.
    Queens University of Belfast, North Ireland.
    Romagnani, L.
    UPMC, France.
    Poder, K.
    Imperial Coll London, England.
    Cole, J. M.
    Imperial Coll London, England.
    Alejo, A.
    Queens University of Belfast, North Ireland.
    Yeung, M.
    Queens University of Belfast, North Ireland.
    Krushelnick, K.
    University of Michigan, MI 48109 USA.
    Mangles, S. P. D.
    Imperial Coll London, England.
    Najmudin, Z.
    Imperial Coll London, England.
    Reville, B.
    Queens University of Belfast, North Ireland.
    Samarin, G. M.
    Queens University of Belfast, North Ireland.
    Symes, D. D.
    Rutherford Appleton Lab, England.
    Thomas, A. G. R.
    University of Michigan, MI 48109 USA; University of Lancaster, England.
    Borghesi, M.
    Queens University of Belfast, North Ireland.
    Sarri, G.
    Queens University of Belfast, North Ireland.
    Experimental Observation of a Current-Driven Instability in a Neutral Electron-Positron Beam2017Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 119, nr 18, artikkel-id 185002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (amp;gt;= 1 T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma. The experimentally determined equipartition parameter of epsilon(B) approximate to 10(-3) is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets.

    Fulltekst (pdf)
    fulltext
  • 1022.
    Weber, Gunther H.
    et al.
    Lawrence Berkeley National Lab, CA 94720 USA; University of Calif Davis, CA 95616 USA.
    Carpendale, Sheelagh
    University of Calgary, Canada.
    Ebert, David
    Purdue University, IN 47907 USA.
    Fisher, Brian
    Simon Fraser University, Canada.
    Hagen, Hans
    University of Kaiserslautern, Germany.
    Shneiderman, Ben
    University of Maryland, MD 20742 USA; US National Academic Engn, DC USA.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Norrkoping Visualizat Centre, Sweden.
    Apply or Die: On the Role and Assessment of Application Papers in Visualization2017Inngår i: IEEE Computer Graphics and Applications, ISSN 0272-1716, E-ISSN 1558-1756, Vol. 37, nr 3, s. 96-104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    n/a

  • 1023.
    Wernersson, Stina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Wigö, Louise
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Hur kan ett mönster på utflyktsprodukter till barn se ut för att passa till ett brett åldersspann?2017Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Syftet med denna studie var att undersöka hur ett mönster på utflyktsprodukter kan se ut för att passa barn i ett brett åldersspann. Idag är många produkter på marknaden riktade till en smal målgrupp, både gällande ålder och kön. Företaget Selvins vill därför skapa produkter som passar till en bred målgrupp för undvika slit och släng av flera olika produkter. Tidigare forskning berör sällan ämnet design kopplat till målgruppens åldrar, varför teorier om barns preferenser för färger och motiv eftersöktes. Som metod användes forskning genom design. En inledande förstudie utfördes för att samla kunskap om vilka åldrar produkter på marknaden riktar sig till, vad som är viktigt att tänka på gällande mönsterdesign till barn samt vad varumärket Selvins står för. Under designprocessen användes lärdomar från förstudien samt tidigare teorier om barns färg- och motivpreferenser i olika åldrar. Det resulterade i att fyra olika mönster skapades. Dessa mönster värderades sedan i kvalitativa intervjuer med 22 barn i åldrar mellan 6-12, samt 15 föräldrar och två designers. Diskussion fördes kring resultatet av varje mönster samt faktorer som kan ha påverkat resultaten. Studien visar att ett av mönstren, som bestod av geometriska former, var omtyckt av barn i alla olika åldrar mellan 6-12 och föräldrar och designers ansåg att det passade en mycket bred åldersgrupp.

    Fulltekst (pdf)
    How can a pattern be designed to attract children of a wide age group within excursion products?
  • 1024.
    Westermark, Erik
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Infographics across media channels2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Studien behandlar publicering av informationsgrafik i de mediala kanalerna tryck och webb, med fokus på de problem och begränsningar som där kan uppstå. Utgångspunkten är intervjuer med skapare av grafik, granskning av publicerad grafik i de olika formaten samt återkoppling till tidigare forskning och teorier.

    Två tidningar, en rikstäckande och en lokal, är representerade i studien. Skillnader dem emellan är framförallt deras förhållningssätt till webbplattformen som medie. Den rikstäckande tidningen satsar mer på publicering i webbkanalen än lokaltidningen. De påverkande faktorer som spelar in, enligt intervjuer med grafikerna, är av författaren kategoriserade som: strategi, teknik, resurser samt läsarens påverkan. Granskningen av den publicerade grafiken visar att båda tidningarna publicerar mer grafik i sin tryckta version än på webben. Storleksmässigt bred tryckt grafik kräver omarbetning för att passa in på respektive webbplats.

    Fulltekst (pdf)
    Infographics across media channels
  • 1025.
    Westin, Carl
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Lundin Palmerius, Karljohan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Johansson, Jimmy
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Lundberg, Jonas
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Concept of Reskilling for Automation Collaboration in Maritime Piloting2019Inngår i: IFAC PAPERSONLINE, ELSEVIER , 2019, Vol. 52, nr 19, s. 365-370Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Advanced automation has been highlighted as contributory to several accidents involving modern bridge support systems and automation aiding maritime pilots for maneuvering and navigation. This paper argues for reskilling for automation collaboration, that operators need training that provides an understanding of what data the automation uses and how, and to transfer this skill to their working environment and be able to make full use of the automation even under influence of inaccurate data. As a case, this paper explores the predictor automation, which is an advanced navigation aid that visualizes an estimation of the ships future trajectory on an electronic chart display. Field studies and a literature review of maritime accidents were carried out to determine difficulties maritime pilots have with understanding the predictor. This research provides valuable guidance for how automation transparency can be an important part of reskilling and how to achieve it. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.

  • 1026.
    Westin, Carl
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Lundin Palmerius, Karljohan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Lundberg, Jonas
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Johansson, Jimmy
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Concept of Reskilling for Automation Collaboration in Maritime Piloting2019Inngår i: Analysis, Design, and Evaluation of Human – Machine Systems, 2019, s. 365-370Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Advanced automation has been highlighted as contributory to several accidents involving modern bridge support systems and automation aiding maritime pilots for maneuvering and navigation. This paper argues for reskilling for automation collaboration, that operators need training that provides an understanding of what data the automation uses and how, and to transfer this skill to their working environment and be able to make full use of the automation even under influence of inaccurate data. As a case, this paper explores the predictor automation, which is an advanced navigation aid that visualizes an estimation of the ship’s future trajectory on an electronic chart display. Field studies and a literature review of maritime accidents were carried out to determine difficulties maritime pilots have with understanding the predictor. This research provides valuable guidance for how automation transparency can be an important part of reskilling and how to achieve it.

  • 1027.
    Westin, Carl
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Vrotsou, Katerina
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Nordman, Aida
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Lundberg, Jonas
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Meyer, Lothar
    Research & Innovation LFV, Norrköping, Sweden.
    Visual Scan Patterns in Tower Control: Foundations for an Instructor Support Tool2019Inngår i: / [ed] Dirk Schaefer, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Although where to look, when, and in what order is crucial for situation awareness and task performance in tower control, instructors are lacking support systems that can help them understand operators’ visual scan behaviours. As a way forward, this paper investigates the existence and characteristics of visual scan patterns in tower control and explores a novel support tool that can help instructors in searching for and exploring these patterns. First, eye-tracking data from two controllers were collected in a high-fidelity tower simulator. Second, a workshop was conducted with three instructors to discuss specific scan patterns that can be expected in relation to the approach scenarios used in the eye-tracking data collection. Six template visual scan patterns were identified during the workshop. Finally, an interactive visual sequence mining tool was used to identify and explore instances of the template scan patterns in the recorded eye-tracking data. Four of these could be detected using the tool: runway scans, landing clearance, touchdown and landing roll, and phases of visual focus. The identification of template scan patterns provides additional insight for formalising controllers’ visual work in tower control. The ability to detect and explore visual scan patterns in the proposed tool shows promise for improving instructors’ understanding of controllers’ visual scan behaviours, and for improving training effectiveness.

  • 1028.
    Wiberg, Benjamin
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Automatic Clustering of 3D Objects for Hierarchical Level-of-Detail2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This report describes an algorithm for computing 3D object hierarchies fit for hlod optimization. The algorithm is used as a pre-processing stage in an hlod pipeline that automatically optimizes 3D models containing multiple meshes. The algorithm for generating hierarchies groups together meshes in a hierarchical tree using operations on bounding spheres of the meshes. The algorithm prioritizes grouping close objects together in the early stages, and relaxes its constraints toward the end, resulting in a tree structure with a single root node. The hierarchical tree is then used by computing proxy meshes, i.e. simplified stand-in meshes, for the inner nodes of the hierarchy. Finally, the resulting proxy meshes, together with the generated hierarchy and the original meshes, are used to render the model using a tree-traversing hlod switching algorithm that renders deeper parts of the tree containing more detailed meshes when more detail is needed. In addition, a minor change to the clustering algorithm is proposed. By swapping the bounding spheres to AABBs (Axis-Aligned Bounding Boxes) in the clustering stage, hierarchies with different properties are generated. This change is shown to generate hierarchies with similar rendering performance as the hierarchies made with bounding spheres, while at the same time resulting in lower space requirements for all proxy meshes. Overall, the proposed automatic hlod pipeline is shown to increase rendering performance for all evaluated scenes in most frames, while never yielding noticeably worse performance than the original model as well.

    Fulltekst (pdf)
    Automatic Clustering of 3D Objects for Hierarchical Level-of-Detail
  • 1029.
    Widgren, Katarina
    et al.
    Public Health Agency Sweden, Sweden; Karolinska Institute, Sweden.
    Skar, Helena
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan. Karolinska Institute, Sweden; Los Alamos National Lab, NM 87545 USA.
    Berglund, Torsten
    Public Health Agency Sweden, Sweden.
    Kling, Anna-Maria
    Public Health Agency Sweden, Sweden.
    Tegnell, Anders
    Public Health Agency Sweden, Sweden.
    Albert, Jan
    Karolinska Institute, Sweden; Karolinska University Hospital, Sweden.
    Delayed HIV diagnosis common in Sweden, 2003-20102014Inngår i: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 46, nr 12, s. 862-867Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Early diagnosis of HIV is important for the prognosis of individual patients, because antiretroviral treatment can be started at the appropriate time, and for public health, because transmission can be prevented. Methods: Data were collected from 767 HIV patients who were diagnosed in Sweden during 2003-2010 and were infected in Sweden or born in Sweden and infected abroad. A recent infection testing algorithm (RITA) was applied to BED-EIA test results (OD-n less than 0.8), CD4 counts (greater than= 200 cells/mu l), and clinical information. A recent infection classification was used as indicator for early diagnosis. Time trends in early diagnosis were investigated to detect population changes in HIV testing behavior. Patients with early diagnosis were compared to patients with delayed diagnosis with respect to age, gender, transmission route, and country of infection (Sweden or abroad). Results: Early diagnosis was observed in 271 patients (35%). There was no statistically significant time trend in the yearly percentage of patients with early diagnosis in the entire study group (p = 0.836) or in subgroups. Early diagnosis was significantly more common in men who have sex men (MSM) (45%) than in heterosexuals (21%) and injecting drug users (27%) (p less than 0.001 and p = 0.001, respectively) in both univariate and multivariable analyses. The only other factor that remained associated with early diagnosis in multivariable analysis was young age group. Conclusion: Approximately one-third of the study patients were diagnosed early with no significant change over time. Delayed HIV diagnosis is a considerable problem in Sweden, which does not appear to diminish.

  • 1030.
    Winblad, Emanuel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Visualization of web site visit and usage data2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This report documents the work and results of a master’s thesis in Media Tech- nology that has been carried out at the Department of Science and Technology at Linköping University with the support of Sports Editing Sweden AB (SES). Its aim is to create a solution which aids the users of SES’ web CMS products in gaining insight into web site visit and usage statistics. The resulting solu- tion is the concept and initial version of a web based service. This service has been developed through an agile process with user centered design in mind and provides a graphical user interface which makes high use of visualizations to achieve the project goal.

    Fulltekst (pdf)
    fulltext
  • 1031.
    Woisetschläger, Mischa
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Röntgenkliniken i Linköping. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Blomma, Johan
    Region Östergötland, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Dahlström, Nils
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Röntgenkliniken i Linköping. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Bivik Stadler, Caroline
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Forsberg, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Liver data from the Visual Sweden project DROID: Analytic Imaging Diagnostics Arena (AIDA)2019Dataset
  • 1032.
    Woisetschläger, Mischa
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Landgren, Filip
    Filip Landgren Consulting, Linköping.
    Bivik Stadler, Caroline
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Forsberg, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Skeletal data from the Visual Sweden project DROID: Analytic Imaging Diagnostics Arena (AIDA)2019Dataset
  • 1033.
    Wolmerud, Markus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Real-Time Fluid Simulation and Visualization2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis presents a method based on Smoothed Particle Hydrodynamics to simulate sparse particle systems with fluid like properties in real-time. The simulation supports interactions with terrain and objects and is scaled depending on activity of the fluid. We use a carpet method on the GPU to visualize the water surface with translucency, reflection, refraction and added topology. Splash effects and foam are imitated and added as a last step.

    Fulltekst (pdf)
    fulltext
  • 1034.
    Wängdahl, Terese
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Inomhusklimat i ett statligt byggnadsminne2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Statliga byggnadsminnen är byggnader som genom dess speciella kulturhistoriska värde är extra viktiga att bevara för framtiden. Att bevara, speciellt äldre byggnader, är inte alltid helt enkelt. En av utmaningarna i detta är att hålla ett lämpligt inomhusklimat i byggnaden för att förhindra en allt för snabb nedbrytningsprocess av material. Det finns tre lämpliga metoder för styrning av inomhusklimatet; Skyddsvärme, avfuktning samt styrd ventilation. Beroende på vad den byggnad eller det rum som studeras skall användas till och hur de unika förutsättningarna ser ut just där kan olika metoder vara olika lämpliga. Studieobjektet i den här rapporten är Salsta slott, här har fyra rum studerats för att avgöra vilken metod som skulle kunna passa i respektive rum. Rummen har aningen olika förutsättningar och behov vilket ger en bra grund till att kunna se hur de skiljer sig vad det gäller lämpliga metoder.

    Fulltekst (pdf)
    fulltext
  • 1035.
    Yao, Jianhua
    et al.
    NIH, MD 20892 USA.
    Burns, Joseph E.
    University of Calif Irvine, CA 92688 USA.
    Forsberg, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Sectra, Linkoping, Sweden.
    Seitel, Alexander
    University of British Columbia, Canada.
    Rasoulian, Abtin
    University of British Columbia, Canada.
    Abolmaesumi, Purang
    University of British Columbia, Canada.
    Hammernik, Kerstin
    Graz University of Technology, Austria.
    Urschler, Martin
    Ludwig Boltzmann Institute Clin Forens Imaging, Austria.
    Ibragimov, Bulat
    University of Ljubljana, Slovenia.
    Korez, Robert
    University of Ljubljana, Slovenia.
    Vrtovec, Tomaz
    University of Ljubljana, Slovenia.
    Castro-Mateos, Isaac
    University of Sheffield, England.
    Pozo, Jose M.
    University of Sheffield, England.
    Frangi, Alejandro F.
    University of Sheffield, England.
    Summers, Ronald M.
    NIH, MD 20892 USA.
    Li, Shuo
    GE Healthcare, Canada; University of Western Ontario, Canada.
    A multi-center milestone study of clinical vertebral CT segmentation2016Inngår i: Computerized Medical Imaging and Graphics, ISSN 0895-6111, E-ISSN 1879-0771, Vol. 49, s. 16-28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A multiple center milestone study of clinical vertebra segmentation is presented in this paper. Vertebra segmentation is a fundamental step for spinal image analysis and intervention. The first half of the study was conducted in the spine segmentation challenge in 2014 International Conference on Medical Image Computing and Computer Assisted Intervention (MICCAI) Workshop on Computational Spine Imaging (CSI 2014). The objective was to evaluate the performance of several state-of-the-art vertebra segmentation algorithms on computed tomography (CT) scans using ten training and five testing dataset, all healthy cases; the second half of the study was conducted after the challenge, where additional 5 abnormal cases are used for testing to evaluate the performance under abnormal cases. Dice coefficients and absolute surface distances were used as evaluation metrics. Segmentation of each vertebra as a single geometric unit, as well as separate segmentation of vertebra substructures, was evaluated. Five teams participated in the comparative study. The top performers in the study achieved Dice coefficient of 0.93 in the upper thoracic, 0.95 in the lower thoracic and 0.96 in the lumbar spine for healthy cases, and 0.88 in the upper thoracic, 0.89 in the lower thoracic and 0.92 in the lumbar spine for osteoporotic and fractured cases. The strengths and weaknesses of each method as well as future suggestion for improvement are discussed. This is the first multi-center comparative study for vertebra segmentation methods, which will provide an up-to-date performance milestone for the fast growing spinal image analysis and intervention. (C) 2016 Elsevier Ltd. All rights reserved.

  • 1036.
    Ynnerman, Anders
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Chapman, S C
    Ljung, Patric
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Andersson, Niclas
    Bifurcation to chaos in charged particle orbits in a magnetic reversal with shear field2002Inngår i: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 30, nr 1, s. 18-19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Regular and stochastic behavior in single particle orbits in static magnetic reversals have wide application in laboratory and physical plasmas. In a simple magnetic reversal, the system has three degrees of freedom but only two global (exact) constants of the motion; the system is nonintegrable and the particle motion can, under certain conditions, exhibit chaotic behavior. Here, we consider the dynamics when a constant shear field is added. In this case, the form of the potential changes from quadratic to velocity dependent.We use numerically integrated trajectories to showthat¨the effect of the shear field is to break the symmetry of the system so that the topology of the invariant tori of regular orbits is changed. In this case, invariant tori take the form of nested Moebius strips in the presence of the shear field. The route to chaos is via bifurcation (period doubling) of the Moebius strip tori.

  • 1037.
    Ynnerman, Anders
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Löwgren, Jonas
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Tibell, Lena
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Utbildningsvetenskap.
    Exploranation: A New Science Communication Paradigm2018Inngår i: IEEE Computer Graphics and Applications, ISSN 0272-1716, E-ISSN 1558-1756, Vol. 38, nr 3, s. 13-20Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Science communication is facing a paradigm shift, based on the convergence of exploratory and explanatory visualization. In this article, we coin the term exploranation to denote the way in which visualization methods from scientific exploration can be used to communicate results and how methods in explanatory visualization can enrich exploration.

    Fulltekst (pdf)
    fulltext
  • 1038.
    Ynnerman, Anders
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Norrkoping Visualizat Centre C, Sweden.
    Rydell, Thomas
    Interspectral AB, Sweden; Interact Institute Swedish ICT, Sweden.
    Antoine, Daniel
    British Museum, England; UCL, England.
    Hughes, David
    Interspectral AB, Sweden; Interact Institute Swedish ICT, Sweden.
    Persson, Anders
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Röntgenkliniken i Linköping. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Ljung, Patric
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Norrkoping Visualizat Centre C, Sweden.
    Interactive Visualization of 3D Scanned Mummies at Public Venues2016Inngår i: Communications of the ACM, ISSN 0001-0782, E-ISSN 1557-7317, Vol. 59, nr 12, s. 72-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BY COMBINING VISUALIZATION techniques with interactive multi-touch tables and intuitive user interfaces, visitors to museums and science centers can conduct self-guided tours of large volumetric image data. In an interactive learning experience, visitors become the explorers of otherwise invisible interiors of unique artifacts and subjects. Here, we take as our starting point the state of the art in scanning technologies, then discuss the latest research on high-quality interactive volume rendering and how it can be tailored to meet the specific demands

  • 1039.
    Ynnerman, Anders
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Rydell, Thomas
    Persson, Anders
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Ernvik, Aron
    Forsell, Camilla
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ljung, Patric
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Lundström, Claes
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Multi-Touch Table System for Medical Visualization2015Inngår i: Eurographics 2015: Dirk Bartz Prize, Eurographics - European Association for Computer Graphics, 2015Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Medical imaging plays a central role in a vast range of healthcare practices. While the usefulness of 3D visualizations is well known, the adoption of such technology has previously been limited in many medical areas. This paper, awarded the Dirk Bartz Prize for Visual Computing in Medicine 2015, describes the development of a medical multi-touch visualization table that successfully has reached its aim to bring 3D visualization to a wider clinical audience. The descriptions summarize the targeted clinical scenarios, the key characteristics of the system, and the user feedback obtained.

  • 1040.
    Zachrisson, Mikael
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    High Quality Shadows for Real-time Surface Visualization2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis describes the implementation of a shadowing system able to produce hard shadows. Shadow mapping is the most common real-time shadowing algorithm but it suffers from severe aliasing artifacts and self-shadowing effects. Different advanced techniques based on Shadow Mapping are implemented in this thesis with the objective of creating accurate hard shadows. First, an implementation based on Cascaded Shadow Maps is presented. This technique improves the visual quality of shadow mapping by using multiple smaller shadow maps instead of a large one. The technique addresses the fact that objects near the viewer require a higher shadow map resolution than objects far away. The second technique presented is Sub-pixel Shadow Mapping. By storing information about occluding triangles in the shadow map this technique is able to produce accurate hard shadows with sub-pixel precision. Both methods can be combined in order to improve the resulting shadow quality. Finally, a collection of advanced biasing techniques that minimize the self-hadowing artifacts generated by shadow mapping are presented. The final implementation achieves real-time performances with considerably improved quality compared to standard shadow mapping.

    Fulltekst (pdf)
    High Quality Shadows for Real-time Surface Visualization
  • 1041.
    Zajac, Jacub
    et al.
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Eriksson, Jonatan
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet.
    Dyverfeldt, Petter
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Bolger, Ann F.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US. Department of Medicine, University of California San Francisco, San Francisco, CA, USA.
    Ebbers, Tino
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Carlhäll, Carl-Johan
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Turbulent Kinetic Energy in Normal and Myopathic Left Ventricles2015Inngår i: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 41, nr 4, s. 1021-1029Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: To assess turbulent kinetic energy (TKE) within the left ventricle (LV) of healthy subjects using novel 4D flow MRI methods and to compare TKE values to those from a spectrum of patients with dilated cardiomyopathy (DCM).

    Methods: 4D flow and morphological MRI-data were acquired in 11 healthy subjects and 9 patients with different degrees of diastolic dysfunction. TKELV was calculated within the LV at each diastolic time frame. At peak early (E) and late (A) diastolic filling, the TKELV was compared to transmitral peak velocity, LV diameter and mitral annular diameter.

    Results: In the majority of all subjects, peaks in TKELV could be observed at E and A. Peak TKELV at E was not different between the groups, and correlated with mitral annular dimensions. Peak TKELV at A was higher in DCM patients compared to healthy subjects, and was related to LV diameter and transmitral velocity.

    Conclusions: In normal LVs, TKE values are low. Values are highest during early diastole, and diminish with increasing LV size. In a heterogeneous group of DCM patients, late diastolic TKE values are higher than in healthy subjects. Kinetic energy loss due to elevated late diastolic TKE may reflect inefficient flow in dilated LVs.

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    Download (mpeg)
    Supplementary film 1
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    Supplementary film 3
  • 1042.
    Zeitler, Jonas
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Adaptive rendering of celestial bodies in WebGL2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This report covers theory and comparison of techniques for rendering massive scale 3D geospa- tial planet data in a web browser. It also presents implementation details of a few of these tech- niques in WebGL and Javascript, using the Three.js [1] 3D library. The thesis project is part of the implementation of Unitea, a web based education platform for interactive astronomy visualizations. Unitea is a derivative of Uniview, which is a fulldome interactive simulation of the universe. A major part of this thesis is dedicated to the implementa- tion of Hierarchical Level of Detail (HLOD) modules for Three.js based on the theory presented by T. Ulrich [2] and later generalized by Cozzi and Ring [3]. HLOD techniques are dynamic level of detail algorithms that represent the surface of objects as accurately as possible from a certain viewing angle. By using space partitioning tree-structures, view based error metrics and culling techniques detailed representations of the objects (in this case planets) can be efficiently rendered in real-time. The modules developed provide a general-purpose library for rendering planets (or other spher- ical objects) with dynamic level of detail in Three.js. The library also features connections to online web map services (WMS) and tile services.

    Fulltekst (pdf)
    fulltext
  • 1043.
    Zitinski Elias, Paula
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Gooran, Sasan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Nyström, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Multilevel Halftoning and Color Separation for Eight-Channel Printing2016Inngår i: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 60, nr 5, artikkel-id 50403Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multichannel printing employs additional colorants to achieve higher quality reproduction, assuming their physical overlap restrictions are met. These restrictions are commonly overcome in the printing workflow by controlling the colorant choice at each point. Our multilevel halftoning algorithm bundles inks of same hues in one channel with no overlap, separating them into eight channels, consequentially benefitting of increased ink options at each point. In this article, implementation and analysis of the algorithm is carried out. Color separation is performed using the cellular Yule‐Nielsen modified spectral Neugebauer model. The channels are binarized with the multilevel halftoning algorithm. The workflow is evaluated with an eight-channel inkjet at 600 dpi resulting in mean and maximum ΔE 94 color differences around 1 and 2, respectively. The halftoning algorithm is analyzed using S-CIELAB, thus involving the human visual system, in which multilevel halftoning showed improvement in terms of image quality compared to the conventional approach.

  • 1044.
    Zitinski Elias, Paula
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Gooran, Sasan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Nyström, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Multilevel halftoning applied to achromatic inks in multi-channel printing2014Inngår i: Abstracts from 41st International research conference of iarigai: Advances in Printing and Media Technology,  Print and media research for the benefit of industry and society, 2014, s. 25-25Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Printing using more than four ink channels visually improves the reproduction. Nevertheless, if the ink layer thickness at any given point exceeds a certain limit, ink bleeding and colour accuracy problems would occur. Halftoning algorithms that process channels dependently are one way of dealing with this shortcoming of multi-channel printing. A multilevel halftoning algorithm that processes a channel so that it is printed with multiple inks of same chromatic value was introduced in our research group. Here we implement this multilevel algorithm using three achromatic inks – photo grey, grey, black – in a real paper-ink setup. The challenges lay in determining the thresholds for ink separation and in dot gain compensation. Dot gain results in a darker reproduction and since it originates from the interaction between a specific ink and paper, compensating the original image for multilevel halftone means expressing dot gain of three inks in terms of the nominal coverage of a single ink. Results prove a successful multilevel halftone implementation workflow using multiple inks while avoiding dot-on-dot placement and accounting for dot gain. Results show the multilevel halftoned image is visually improved in terms of graininess and detail enhancement when compared to the bi-level halftoned image.

    Fulltekst (pdf)
    fulltext
  • 1045.
    Zitinski Elias, Paula
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Gooran, Sasan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Nyström, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    MULTILEVEL HALFTONING AS AN ALGORITHM TO CONTROL INK OVERLAP IN MULTI-CHANNEL PRINTING2015Inngår i: 2015 COLOUR AND VISUAL COMPUTING SYMPOSIUM (CVCS), IEEE , 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A multilevel halftoning algorithm can be used to overcome some of the challenges of multi-channel printing. In this algorithm, each channel is processed so that it can be printed using multiple inks of approximately the same hue, achieving a single ink layer. The computation of the threshold values required for ink separation and dot gain compensation pose an interesting challenge. Since the dot gain depends on the specific combination of ink, paper and print resolution, compensating the original image for multilevel halftoning means expressing the dot gain of multiple inks of same hue in terms of the coverage of a single ink. The applicability of the proposed multilevel halftoning workflow is demonstrated using chromatic inks while avoiding dot overlap and accounting for dot gain. The results indicate that the multilevel halftoned image is visually improved in terms of graininess when compared to bi-level halftoned images.

  • 1046.
    Zitinski Elias, Paula
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Nyström, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Gooran, Sasan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Color separation for improved perceived image quality in terms of graininess and gamut2017Inngår i: Color Research and Application, ISSN 0361-2317, E-ISSN 1520-6378, Vol. 42, nr 4, s. 486-497Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-channel printing employs additional inks to improve the perceived image quality by reducing the graininess and augmenting the printer gamut. It also requires a color separation that deals with the one-to-many mapping problem imposed when using more than three inks. The proposed separation model incorporates a multilevel halftoning algorithm, reducing the complexity of the print characterization by grouping inks of similar hues in the same channel. In addition, a cost function is proposed that weights selected factors influencing the print and perceived image quality, namely color accuracy, graininess and ink consumption. The graininess perception is qualitatively assessed using S-CIELAB, a spatial low-pass filtering mimicking the human visual system. By applying it to a large set of samples, a generalized prediction quantifying the perceived graininess is carried out and incorporated as a criterion in the color separation. The results of the proposed model are compared with the separation giving the best colorimetric match, showing improvements in the perceived image quality in terms of graininess at a small cost of color accuracy and ink consumption. (c) 2016 Wiley Periodicals, Inc.

  • 1047.
    Zitinski Elias, Paula
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Nyström, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Gooran, Sasan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Multi-channel printing by orthogonal and non-orthogonal AM halftoning2013Inngår i: Proceedings of 12th International AIC Colour Congress: Bringing Colour to Life, Newcastle, UK, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Multi-channel printing with more than the conventional four colorants brings numerous advantages, but also challenges, like implementation of halftone algorithms. This paper concentrates on amplitude modulated (AM) halftoning for multi-channel printing. One difficulty is the correct channel rotation to avoid the moiré effect and to achieve colour fidelity in case of misregistration. 20 test patches were converted to seven-channel images and AM halftoning was applied using two different approaches in order to obtain a moiré-free impression. One method was to use orthogonal screens and adjust the channels by overlapping the pairs of complimentary colours, while the second was to implement non-orthogonal halftone screens (ellipses). By doing so, a wider angle range is available to accommodate a seven-channel impression. The performance was evaluated by simulating misregistration in both position and angle for a total of 1600 different scenarions. ΔE values were calculated between the misregistered patches and the correct ones, for both orthogonal and non-orthogonal screens. Results show no visible morié and improvement in colour fidelity when using non-orthogonal screens for seven-channel printing, producing smaller colour differences in case of misregistration.

  • 1048.
    Zobel, Valentin
    et al.
    Leipzig University, Leipzig, Germany.
    Reininghaus, Jan
    Institute of Science and Technology Austria, Klosterneuburg, Austria.
    Hotz, Ingrid
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Visualizing Symmetric Indefinite 2D Tensor Fields using the Heat Kernel Signature2015Inngår i: Visualization and Processing of Tensors and Higher Order Descriptors for Multi-Valued Data / [ed] Ingrid Hotz, Thomas Schultz, Cham: Springer, 2015, s. 257-267Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The Heat Kernel Signature (HKS) is a scalar quantity which is derived from the heat kernel of a given shape. Due to its robustness, isometry invariance, and multiscale nature, it has been successfully applied in many geometric applications. From a more general point of view, the HKS can be considered as a descriptor of the metric of a Riemannian manifold. Given a symmetric positive definite tensor field we may interpret it as the metric of some Riemannian manifold and thereby apply the HKS to visualize and analyze the given tensor data. In this paper, we propose a generalization of this approach that enables the treatment of indefinite tensor fields, like the stress tensor, by interpreting them as a generator of a positive definite tensor field. To investigate the usefulness of this approach we consider the stress tensor from the two-point-load model example and from a mechanical work piece.

  • 1049.
    Zografos, Vasileios
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Lenz, Reiner
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Spatio-chromatic image content descriptors and their analysis using Extreme Value Theory2011Inngår i: Image analysis: 17th Scandinavian Conference, SCIA 2011, Ystad, Sweden, May 2011. Proceedings, Springer Berlin/Heidelberg, 2011, s. 579-591Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We use the theory of group representations to construct very fast image descriptors that split the vector space of local RGB distributions into small group-invariant subspaces. These descriptors are group theoretical generalizations of the Fourier Transform and can be computed with algorithms similar to the FFT. Because of their computational efficiency they are especially suitable for retrieval, recognition and classification in very large image datasets. We also show that the statistical properties of these descriptors are governed by the principles of the Extreme Value Theory (EVT). This enables us to work directly with parametric probability distribution models, which offer a much lower dimensionality and higher resolution and flexibility than explore the connection to EVT and analyse the characteristics of these descriptors from a probabilistic viewpoint with the help of large image databases.

    Fulltekst (pdf)
    scia2011
  • 1050.
    Zografos, Vasileios
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Lenz, Reiner
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Ringaby, Erik
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Nordberg, Klas
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Fast segmentation of sparse 3D point trajectories using group theoretical invariants2015Inngår i: COMPUTER VISION - ACCV 2014, PT IV / [ed] D. Cremers, I. Reid, H. Saito, M.-H. Yang, Springer, 2015, Vol. 9006, s. 675-691Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a novel approach for segmenting different motions from 3D trajectories. Our approach uses the theory of transformation groups to derive a set of invariants of 3D points located on the same rigid object. These invariants are inexpensive to calculate, involving primarily QR factorizations of small matrices. The invariants are easily converted into a set of robust motion affinities and with the use of a local sampling scheme and spectral clustering, they can be incorporated into a highly efficient motion segmentation algorithm. We have also captured a new multi-object 3D motion dataset, on which we have evaluated our approach, and compared against state-of-the-art competing methods from literature. Our results show that our approach outperforms all methods while being robust to perspective distortions and degenerate configurations.

    Fulltekst (pdf)
    fulltext
1819202122 1001 - 1050 of 1058
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