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  • 1551.
    Witschard, Daniel
    et al.
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Jusufi, Ilir
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus University, Sweden.
    SimBaTex: Similarity-based Text Exploration2021In: Posters of the 23rd EG/VGTC Conference on Visualization (EuroVis '21) / [ed] Jan Byška, Stefan Jänicke, and Johanna Schmidt, Eurographics - European Association for Computer Graphics, 2021, p. 5-7Conference paper (Refereed)
    Abstract [en]

    Natural language processing in combination with visualization can provide efficient ways to discover latent patterns of similarity which can be useful for exploring large sets of text documents. In this poster abstract, we describe the ongoing work on a visual analytics application, called SimBaTex, which is based on embedding technology, dynamic specification of similarity criteria, and a novel approach for similarity-based clustering. The goal of SimBaTex is to provide search-and-explore functionality to enable the user to identify items of interest in a large set of text documents by interactive assessment of both high-level similarity patterns and pairwise similarity of chosen texts.

  • 1552.
    Witschard, Daniel
    et al.
    Linnaeus Univ, Sweden.
    Jusufi, Ilir
    Blekinge Inst Technol, Sweden.
    Kucher, Kostiantyn
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus Univ, Sweden.
    Visually Guided Network Reconstruction Using Multiple Embeddings2023In: Proceedings of the 16th IEEE Pacific Visualization Symposium (PacificVis '23), visualization notes track, IEEE, 2023, IEEE , 2023, p. 212-216Conference paper (Refereed)
    Abstract [en]

    Embeddings are powerful tools for transforming complex and unstructured data into numeric formats suitable for computational analysis tasks. In this paper, we extend our previous work on using multiple embeddings for text similarity calculations to the field of networks. The embedding ensemble approach improves network reconstruction performance compared to single-embedding strategies. Our visual analytics methodology is successful in handling both text and network data, which demonstrates its generalizability beyond its originally presented scope.

  • 1553.
    Witschard, Daniel
    et al.
    Linnaeus Univ, Sweden.
    Jusufi, Ilir
    Linnaeus Univ, Sweden.
    Martins, Rafael M.
    Linnaeus Univ, Sweden.
    Kucher, Kostiantyn
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus Univ, Sweden.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus Univ, Sweden.
    Interactive optimization of embedding-based text similarity calculations2022In: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 21, no 4, p. 335-353Article in journal (Refereed)
    Abstract [en]

    Comparing text documents is an essential task for a variety of applications within diverse research fields, and several different methods have been developed for this. However, calculating text similarity is an ambiguous and context-dependent task, so many open challenges still exist. In this paper, we present a novel method for text similarity calculations based on the combination of embedding technology and ensemble methods. By using several embeddings, instead of only one, we show that it is possible to achieve higher quality, which in turn is a key factor for developing high-performing applications for text similarity exploitation. We also provide a prototype visual analytics tool which helps the analyst to find optimal performing ensembles and gain insights to the inner workings of the similarity calculations. Furthermore, we discuss the generalizability of our key ideas to fields beyond the scope of text analysis.

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  • 1554.
    Woisetschläger, Mischa
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Blomma, Johan
    Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Dahlström, Nils
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bivik Stadler, Caroline
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Forsberg, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Liver data from the Visual Sweden project DROID: Analytic Imaging Diagnostics Arena (AIDA)2019Data set
  • 1555.
    Woisetschläger, Mischa
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Landgren, Filip
    Filip Landgren Consulting, Linköping.
    Bivik Stadler, Caroline
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Forsberg, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Skeletal data from the Visual Sweden project DROID: Analytic Imaging Diagnostics Arena (AIDA)2019Data set
  • 1556.
    Wolmerud, Markus
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Real-Time Fluid Simulation and Visualization2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

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  • 1557.
    Wängdahl, Terese
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Inomhusklimat i ett statligt byggnadsminne2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    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.

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  • 1558.
    Wärnå, Alva
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lacorazza, Constanza
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Sorty: Digital Planner: En mobilapplikation för att underlätta produktivitet2022Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    After two years of pandemic and social distancing, students have slowly but surely begun to return to campus for on-site studies. However, the pandemic has taken its toll on motivation and productivity, which has suffered. In today's society, we now solve most of our problems with digital tools, especially mobile applications, and many people now have different applications for different purposes. It is also common for notifications to make themselves heard from time to time. We felt that this was not an optimal way to deal with declining motivation and productivity, so we wanted to prototype an All-in-One application that helps students with productivity, scheduling and focus – no matter where they are.The study's methodology consisted of the four phases of pre-study, concept phase, processing phase and detailing phase. In these phases, a problem related to productivity and motivation has been identified within the target group. Thus, features for the application have been developed based on these findings and other theories. The application has then been evaluated by performing user tests on prototypes with different levels of detail, semi-structured interviews have been conducted and also a SUS score has been developed to evaluate the usability of the prototype. The conclusion of this study resulted in a T-prototype for the Sorty application with the optimized main functions Calendar and Schedule, To-Do List, Pomodoro function and Notification settings. The application was perceived by test participants to increase productivity during a working day.

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  • 1559.
    Wästling, Anna
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Stepwise Teleportation as an Alternative to Continuous Motion in Virtual Reality2023Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the locomotion design space, artificial locomotion is most commonly used when navigating virtual spaces larger than the physical space provided. Some significant challenges to the use of artificial locomotion are however cybersickness and disorientation. Cybersickness is a phenomenon that creates discomfort for the user and is believed to be inflicted by continuous movement and its creation of vection. Contrarily, discrete locomotion interfaces like teleportation do not cause vection or cybersickness for the user. However, because of this, teleportation is unable to offer spatial updating, which is crucial for preventing disorientation. This thesis investigates an alternative to these interfaces that aims to combine their benefits while avoiding their drawbacks in an interface referred to as Stepwise teleportation that consist of short discrete translations, referred to as steps, in the direction chosen by the user.

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  • 1560.
    Yan, Lin
    et al.
    University of Utah, Salt Lake City, Utah, United States.
    Masood, Talha Bin
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Rasheed, Farhan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hotz, Ingrid
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Wang, Bei
    University of Utah, Salt Lake City, Utah, United States.
    Geometry Aware Merge Tree Comparisons for Time-Varying Data with Interleaving Distances2023In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 29, no 8, p. 3489-3506Article in journal (Refereed)
    Abstract [en]

    Merge trees, a type of topological descriptor, serve to identify and summarize the topological characteristics associated with scalar fields. They present a great potential for the analysis and visualization of time-varying data. First, they give compressed and topology-preserving representations of data instances. Second, their comparisons provide a basis for studying the relations among data instances, such as their distributions, clusters, outliers, and periodicities. A number of comparative measures have been developed for merge trees. However, these measures are often computationally expensive since they implicitly consider all possible correspondences between critical points of the merge trees. In this paper, we perform geometry-aware comparisons of merge trees. The main idea is to decouple the computation of a comparative measure into two steps: a labeling step that generates a correspondence between the critical points of two merge trees, and a comparison step that computes distances between a pair of labeled merge trees by encoding them as matrices. We show that our approach is general, computationally efficient, and practically useful. Our general framework makes it possible to integrate geometric information of the data domain in the labeling process. At the same time, it reduces the computational complexity since not all possible correspondences have to be considered. We demonstrate via experiments that such geometry-aware merge tree comparisons help to detect transitions, clusters, and periodicities of a time-varying dataset, as well as to diagnose and highlight the topological changes between adjacent data instances.

  • 1561.
    Yan, Lin
    et al.
    Scientific Computing and Imaging Institute, University of Utah, USA.
    Masood, Talha Bin
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Sridharamurthy, Raghavendra
    Department of Computer Science and Automation, Indian Institute of Science Bangalore, India.
    Rasheed, Farhan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Natarajan, Vijay
    Department of Computer Science and Automation, Indian Institute of Science Bangalore, India.
    Hotz, Ingrid
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Wang, Bei
    Scientific Computing and Imaging Institute, University of Utah, USA.
    Scalar Field Comparison with Topological Descriptors: Properties and Applications for Scientific Visualization2021In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 40, no 3, p. 599-633Article in journal (Refereed)
    Abstract [en]

    In topological data analysis and visualization, topological descriptors such as persistence diagrams, merge trees, contour trees, Reeb graphs, and Morse–Smale complexes play an essential role in capturing the shape of scalar field data. We present a state-of-the-art report on scalar field comparison using topological descriptors. We provide a taxonomy of existing approaches based on visualization tasks associated with three categories of data: single fields, time-varying fields, and ensembles. These tasks include symmetry detection, periodicity detection, key event/feature detection, feature tracking, clustering, and structure statistics. Our main contributions include the formulation of a set of desirable mathematical and computational properties of comparative measures, and the classification of visualization tasks and applications that are enabled by these measures.

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  • 1562.
    Yantseva, Victoria
    et al.
    Linnaeus University, Sweden.
    Kucher, Kostiantyn
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus University, Sweden.
    Machine Learning for Social Sciences: Stance Classification of User Messages on a Migrant-Critical Discussion Forum2021In: Proceedings of the 2021 Swedish Workshop on Data Science (SweDS) / [ed] Rafael M. Martins, Morgan Ericsson, Danny Weyns, Kostiantyn Kucher, IEEE , 2021Conference paper (Refereed)
    Abstract [en]

    In this paper, we present our methodology for supervised stance classification of sparse and imbalanced social media data. We test our framework on a manually labeled dataset of 5700 messages about immigration in the Swedish language posted on the Flashback forum, a controversial online discussion platform. Our proposed approach currently achieves a macro- averaged F1-score of 0.72 for test data on a two-class problem compared against 0.27 for a baseline four-class model. Since effective classification of imbalanced and sparse textual data in under-resourced languages presents certain methodological challenges, our study contributes to a discussion on the best pathways to achieve highest model performance given the character of the data and unavailability of large training datasets for this task. Moreover, this work exemplifies the application of ML methodology to social media data, which can be particularly relevant for social scientists working in this area and interested in leveraging the possibilities of machine learning in their research field. This methodology and the obtained results provide a foundation for further in-depth analyses of social media texts in the Swedish language following a data-driven approach.

  • 1563.
    Yantseva, Victoria
    et al.
    Infolab, Department of Information Technology, Uppsala University, Sweden.
    Kucher, Kostiantyn
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Department of Computer Science and Media Technology, Linnaeus University, Sweden.
    Stance Classification of Social Media Texts for Under-Resourced Scenarios in Social Sciences2022In: Data, E-ISSN 2306-5729, Vol. 7, no 11, article id 159Article in journal (Refereed)
    Abstract [en]

    In this work, we explore the performance of supervised stance classification methods for social media texts in under-resourced languages and using limited amounts of labeled data. In particular, we focus specifically on the possibilities and limitations of the application of classic machine learning versus deep learning in social sciences. To achieve this goal, we use a training dataset of 5.7K messages posted on Flashback Forum, a Swedish discussion platform, further supplemented with the previously published ABSAbank-Imm annotated dataset, and evaluate the performance of various model parameters and configurations to achieve the best training results given the character of the data. Our experiments indicate that classic machine learning models achieve results that are on par or even outperform those of neural networks and, thus, could be given priority when considering machine learning approaches for similar knowledge domains, tasks, and data. At the same time, the modern pre-trained language models provide useful and convenient pipelines for obtaining vectorized data representations that can be combined with classic machine learning algorithms. We discuss the implications of their use in such scenarios and outline the directions for further research.

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  • 1564.
    Yao, Jianhua
    et al.
    NIH, MD 20892 USA.
    Burns, Joseph E.
    University of Calif Irvine, CA 92688 USA.
    Forsberg, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (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 segmentation2016In: Computerized Medical Imaging and Graphics, ISSN 0895-6111, E-ISSN 1879-0771, Vol. 49, p. 16-28Article in journal (Refereed)
    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.

  • 1565.
    Ynnerman, Anders
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Chapman, S C
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Andersson, Niclas
    Bifurcation to chaos in charged particle orbits in a magnetic reversal with shear field2002In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 30, no 1, p. 18-19Article in journal (Refereed)
    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.

  • 1566.
    Ynnerman, Anders
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Persson, Anders
    Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Jönsson, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Multi-Touch Surfaces and Patient-Specific Data2021In: Digital Anatomy: Applications of Virtual, Mixed and Augmented Reality / [ed] Jean-François Uhl, Joaquim Jorge, Daniel Simões Lopes, Pedro F. Campos, Springer, 2021, 1, p. 223-242Chapter in book (Refereed)
    Abstract [en]

    While the usefulness of 3D visualizations has been shown for a range of clinical applications such as treatment planning it still had difficulties in being adopted in widespread clinical practice. This chapter describes how multi-touch surfaces with patient-specific data have contributed to breaking this barrier, paving the way for adoption into clinical practice and, at the same time, also found widespread use in educational settings and in communication of science to the general public. The key element identified for this adoption is the string of steps found in the full imaging chain, which will be described as an introduction to the topic in this chapter. Emphasis in the chapter is, however, visualization aspects, e.g., intuitive interaction with patient-specific data captured with the latest high speed and high-quality imaging modalities. A necessary starting point for this discussion is the foundations of and state-of-the-art in volumetric rendering, which form the basis for the underlying theory part of the chapter. The chapter presents two use cases. One case is focusing on the use of multi-touch in medical education and the other is focusing on the use of touch surfaces at public venues, such as science centers and museums. 

  • 1567.
    Ynnerman, Anders
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Löwgren, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Tibell, Lena
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Educational Sciences.
    Exploranation: A New Science Communication Paradigm2018In: IEEE Computer Graphics and Applications, ISSN 0272-1716, E-ISSN 1558-1756, Vol. 38, no 3, p. 13-20Article in journal (Other academic)
    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.

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  • 1568.
    Ynnerman, Anders
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). 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
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Norrkoping Visualizat Centre C, Sweden.
    Interactive Visualization of 3D Scanned Mummies at Public Venues2016In: Communications of the ACM, ISSN 0001-0782, E-ISSN 1557-7317, Vol. 59, no 12, p. 72-81Article in journal (Refereed)
    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

  • 1569.
    Ynnerman, Anders
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Rydell, Thomas
    Persson, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Ernvik, Aron
    Forsell, Camilla
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ljung, Patric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lundström, Claes
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Multi-Touch Table System for Medical Visualization2015In: Eurographics 2015: Dirk Bartz Prize, Eurographics - European Association for Computer Graphics, 2015Conference paper (Other academic)
    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.

  • 1570.
    Yu, Jinwoo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    An application that creates loops out of audio recordings2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    En applikation för mobila enheter skapades för en målgrupp som bestod av barn i åldern 6–10 år. Applikationen ingick som en del av en större applikation som hette Clappen, som bestod av flera mindre applikationer. Clappen utvecklades av forskningsinstitutet RISE Interactive på uppdrag av Östergötlands sjukhusclowner, som arbetar med att besöka barn på sjukhus i Östergötland. Med lek, gestaltning och musik ger Östergötlands sjukhusclowner barnen en paus i vardagen. Clappens syfte var att förlänga närvaron av clownerna på sjukhuset. Applikationen som beskrivs i detta examensarbete hade som syfte att tillåta barn att skapa musik utan att behöva ha taktkänsla eller förmågan att sjunga i korrekt tonhöjd. Funktionalitet för inspelning implementerades i applikationen och varje inspelning korrigerades med följande ljudmanipulationer: filtrering, analys med Fast Fourier Transform, sample slicing, tonhöjdsbyte med en fasvokoder, fade och kvantisering. Det grafiska gränssnittet utvecklades med följande metoder: fältstudie, effektkarta, prototyper, designmetoden “Crazy eights“ och användartest. Resultatet blev ett grafiskt gränssnitt som tilltalade målgruppen och som enligt användartestet var snabbt och enkelt för målgruppen att lära sig.

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  • 1571.
    Yu, Jinwoo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    En applikation som skapar slingor av ljudinspelningar2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    En applikation för mobila enheter skapades för en målgrupp som bestod av barn i åldern 6–10 år.Applikationen ingick som en del av en större applikation som hette Clappen, som bestod av fleramindre applikationer. Clappen utvecklades av forskningsinstitutet RISE Interactive på uppdrag avÖstergötlands sjukhusclowner, som arbetar med att besöka barn på sjukhus i Östergötland. Med lek,gestaltning och musik ger Östergötlands sjukhusclowner barnen en paus i vardagen. Clappens syftevar att förlänga närvaron av clownerna på sjukhuset.Applikationen som beskrivs i detta examensarbete hade som syfte att tillåta barn att skapa musikutan att behöva ha taktkänsla eller förmågan att sjunga i korrekt tonhöjd. Funktionalitet för inspelningimplementerades i applikationen och varje inspelning korrigerades med följande ljudmanipulationer:filtrering, analys med Fast Fourier Transform, sample slicing, tonhöjdsbyte med en fasvokoder, fadeoch kvantisering. Det grafiska gränssnittet utvecklades med följande metoder: fältstudie, effektkarta,prototyper, designmetoden “Crazy eights“ och användartest. Resultatet blev ett grafiskt gränssnitt somtilltalade målgruppen och som enligt användartestet var snabbt och enkelt för målgruppen att lära sig. 

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  • 1572.
    Yu, Peilin
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Nordman, Aida
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Meyer, Lothar
    Swedish Air Nav Serv, LFV, Linkoping, Sweden.
    Boonsong, Supathida
    Swedish Air Nav Serv, LFV, Linkoping, Sweden.
    Vrotsou, Katerina
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Medicine and Health Sciences.
    Interactive Transformations and Visual Assessment of Noisy Event Sequences: An Application in En-Route Air Traffic Control2023In: 2023 IEEE 16TH PACIFIC VISUALIZATION SYMPOSIUM, PACIFICVIS, IEEE COMPUTER SOC , 2023, p. 92-101Conference paper (Refereed)
    Abstract [en]

    Real-world event sequence data, such as activity logs, eye-tracking data, simulation data, and electronic health records, often share characteristics such as a large alphabet of events, fragmentation, noise, and high complexity which makes them difficult to analyze in their raw form. Because of this, simplification and preprocessing through various data transformations are commonly required before the data can be effectively visualized and analyzed. Existing methods for such data transformation are either manually applied and rely heavily on user expertise, or use algorithmic approaches to apply bulk operations which can imply the loss of potentially important information without users being aware. To bridge this gap, we propose a visual analytics approach that aims to successively increase the quality of noisy event sequences by supporting an interactive, context-aware application of data transformations. This is achieved by providing cues concerning the potential loss of information that transformation operations may imply and allowing users to explore, and visually assess their impact on the data. Therefore, a central feature of the approach is that users can tune the data transformation process so that important identified data characteristics are preserved. We motivate the proposed approach in the domain of air traffic control and illustrate it through a usage example, using event sequences derived by merging eye-tracking and simulator data from a human-in-the-loop simulation experiment with 14 air traffic controllers.

  • 1573.
    Zachrisson, Mikael
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    High Quality Shadows for Real-time Surface Visualization2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

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  • 1574.
    Zahabi, Najmeh
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Baryshnikov, Glib
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Linares, Mathieu
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Charge carrier dynamics in conducting polymer PEDOT using ab initio molecular dynamics simulations2023In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 159, no 15, article id 154801Article in journal (Refereed)
    Abstract [en]

    As conducting polymers become increasingly important in electronic devices, understanding their charge transport is essential for material and device development. Various semi-empirical approaches have been used to describe temporal charge carrier dynamics in these materials, but there have yet to be any theoretical approaches utilizing ab initio molecular dynamics. In this work, we develop a computational technique based on ab initio Car-Parrinello molecular dynamics to trace charge carrier temporal motion in archetypical conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Particularly, we analyze charge dynamics in a single PEDOT chain and in two coupled chains with different degrees of coupling and study the effect of temperature. In our model we first initiate a positively charged polaron (compensated by a negative counterion) at one end of the chain, and subsequently displace the counterion to the other end of the chain and trace polaron dynamics in the system by monitoring bond length alternation in the PEDOT backbone and charge density distribution. We find that at low temperature (T = 1 K) the polaron distortion gradually disappears from its initial location and reappears near the new position of the counterion. At the room temperature (T = 300 K), we find that the distortions induced by polaron, and atomic vibrations are of the same magnitude, which makes tracking the polaron distortion challenging because it is hidden behind the temperature-induced vibrations. The novel approach developed in this work can be used to study polaron mobility along and between the chains, investigate charge transport in highly doped polymers, and explore other flexible polymers, including n-doped ones.

  • 1575.
    Zajac, Jacub
    et al.
    Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Eriksson, Jonatan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences.
    Dyverfeldt, Petter
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bolger, Ann F.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Department of Medicine, University of California San Francisco, San Francisco, CA, USA.
    Ebbers, Tino
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Carlhäll, Carl-Johan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Turbulent Kinetic Energy in Normal and Myopathic Left Ventricles2015In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 41, no 4, p. 1021-1029Article in journal (Refereed)
    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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  • 1576.
    Zeitler, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Adaptive rendering of celestial bodies in WebGL2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

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  • 1577.
    Zhang, Fan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Global Illumination on Modern GPUs2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis that implemented Monte Carlo path tracing and voxel cone tracing for global illumination on GPU compared the performance and visual result. The Monte Carlo path tracing algorithm is implemented in CUDA to do parallel computing on GPU and accelerate the computing speed. The voxel cone tracing, a global illumination algorithm for real-time computing, runs on OpenGL through the GPU graphics pipeline. The results show that the Monte Carlo Path Tracing on CPU single core takes over 10 hours, around 4 hours with 4 cores, on GPU it takes around 48 minutes, while the voxel cone tracing on the same GPU takes 2 ms. The quality of the image generated by the Monte Carlo path tracing contains much more transparent, reflection, and shadow details than that using the voxel cone tracing algorithm.

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  • 1578.
    Zhao, Heyi
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Design of Improving the Self-healing Experiences: - The Quantitative and Qualitative Studies Focus on the Offline and Online Environments2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    People in different environments encounter various mood disorders. The flattened internet perhaps offered chances for conveying more balanced therapy resources. 

    This study starts by considering the multiple environments of self-healing experience and focuses on groups in need of self-healing. The theories consist of the offline to online environments and the interaction between representations, the processes of co-design, and the application of cognitive therapy approaches and trauma design tools.  

    The methods include Research Through Design and Mixed methods research. Qualitative research included an interview attached to the questionnaire, and a workshop could make participants share, learn, and change. The methods are applied to execution and combine the theories' interpretation to contribute to the result. The design results give the target group a more free and less financially stressful way to heal themselves. 

    This thesis finds the requirements of adjusting changeable and chronic twisted cognition, combining the co-design process to incorporate the contribution of participants and the professional therapy resources.

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  • 1579.
    Zhong, Weixian
    et al.
    Nanyang Technol Univ, Singapore.
    Alam, Sameer
    Nanyang Technol Univ, Singapore; Nanyang Technol Univ, Singapore.
    Lim, Yixiang
    Nanyang Technol Univ, Singapore.
    Lilith, Nimrod
    Nanyang Technol Univ, Singapore.
    Josefsson, Billy
    Air Nav Serv Sweden LFV, Sweden.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Bång, Magnus
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    NIRS-based Cognitive Assessment of Safety-Critical Air Traffic Operations2021In: 2021 9TH IEEE INTERNATIONAL WINTER CONFERENCE ON BRAIN-COMPUTER INTERFACE (BCI), IEEE , 2021, p. 302-307Conference paper (Refereed)
    Abstract [en]

    Given the portability and minimal intrusiveness of Near Infrared Spectroscopy (NIRS), there is potential for it to be used in an ecological setting, as compared to classical neuroimaging methods. In this paper, NIRS was used to assess the cognitive processes of operators performing complex, safety-critical Air Traffic Control (ATC) tasks. The haemodynamic response in the Prefrontal Cortex (PFC) was obtained from an event-based analysis of the NIRS recordings. Despite the relative complexity of the experimental scenario, grand-averaged results from the analysis showed an evident Haemodynamic Response Function (HRF) in the right PFC, specifically for events in which the operator provided instructions to arriving aircraft (e.g., clear-to-land or go-around). The HRF peak was observed before the event, suggesting that maximum cognitive processing of the operator occurred before instructions were actually given. Overall, the study supports the suitability of NIRS as a tool for assessing the cognitive processes of operators in ecological settings, demonstrating the potential validity of NIRS-based measurements for BCI systems in safety-critical operations.

  • 1580.
    Ziemer, Tim
    et al.
    University of Hamburg, Germany.
    Lenzi, Sara
    Delft University of Technology, Netherlands.
    Rönnberg, Niklas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hermann, Thomas
    Bielefeld University, Germany.
    Bresin, Roberto
    KTH Royal Institute of Technology, Sweden.
    Introduction to the special issue on design and perception of interactive sonification2023In: Journal on Multimodal User Interfaces, ISSN 1783-7677, E-ISSN 1783-8738, Vol. 17, p. 213-214Article in journal (Other academic)
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  • 1581.
    Zitinski Elias, Paula
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Multilevel Halftoning and Color Separation for Eight-Channel Printing2016In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 60, no 5, article id 50403Article in journal (Refereed)
    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.

  • 1582.
    Zitinski Elias, Paula
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Multilevel halftoning applied to achromatic inks in multi-channel printing2014In: 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, p. 25-25Conference paper (Other academic)
    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.

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  • 1583.
    Zitinski Elias, Paula
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    MULTILEVEL HALFTONING AS AN ALGORITHM TO CONTROL INK OVERLAP IN MULTI-CHANNEL PRINTING2015In: 2015 COLOUR AND VISUAL COMPUTING SYMPOSIUM (CVCS), IEEE , 2015Conference paper (Refereed)
    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.

  • 1584.
    Zitinski Elias, Paula
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Color separation for improved perceived image quality in terms of graininess and gamut2017In: Color Research and Application, ISSN 0361-2317, E-ISSN 1520-6378, Vol. 42, no 4, p. 486-497Article in journal (Refereed)
    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.

  • 1585.
    Zitinski Elias, Paula
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Multi-channel printing by orthogonal and non-orthogonal AM halftoning2013In: Proceedings of 12th International AIC Colour Congress: Bringing Colour to Life, Newcastle, UK, 2013Conference paper (Refereed)
    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.

  • 1586.
    Zobel, Valentin
    et al.
    Leipzig University, Leipzig, Germany.
    Reininghaus, Jan
    Institute of Science and Technology Austria, Klosterneuburg, Austria.
    Hotz, Ingrid
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Visualizing Symmetric Indefinite 2D Tensor Fields using the Heat Kernel Signature2015In: Visualization and Processing of Tensors and Higher Order Descriptors for Multi-Valued Data / [ed] Ingrid Hotz, Thomas Schultz, Cham: Springer, 2015, p. 257-267Chapter in book (Refereed)
    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.

  • 1587.
    Zografos, Vasileios
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Lenz, Reiner
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Spatio-chromatic image content descriptors and their analysis using Extreme Value Theory2011In: Image analysis: 17th Scandinavian Conference, SCIA 2011, Ystad, Sweden, May 2011. Proceedings, Springer Berlin/Heidelberg, 2011, p. 579-591Conference paper (Refereed)
    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.

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    scia2011
  • 1588.
    Zografos, Vasileios
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Lenz, Reiner
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ringaby, Erik
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Nordberg, Klas
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Fast segmentation of sparse 3D point trajectories using group theoretical invariants2015In: COMPUTER VISION - ACCV 2014, PT IV / [ed] D. Cremers, I. Reid, H. Saito, M.-H. Yang, Springer, 2015, Vol. 9006, p. 675-691Conference paper (Refereed)
    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.

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  • 1589. Order onlineBuy this publication >>
    Zohrevandi, Elmira
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Real-Time Visual Analytics Interfaces to Strengthen Human-Automation Collaboration2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Automation in today’s world supports human operators to accomplish several tasks in limited time. With more advanced automation and autonomous systems, the hu-mans’ role is shifting from hands-on operational tasks to supervisory tasks. In complex environments such as air traffic control, supervisory tasks become difficult to manage during unexpected situations as the operator needs to have a clear understanding of various resolution strategies and their consequences and make decisions about them in a limited amount of time (i.e. within a couple of minutes). In such environments, interface designers must carefully consider how information should be presented to the operators. An improper way of presenting information could, wastefully consume operators’ cognitive resources resulting in inefficient decision-making and an increased risk of failure. 

    By designing ecological visual analytics interfaces, this thesis addresses the problem of real-time decision-making in the domain of air traffic control. The aim of this thesis has been to apply ecological design theories to the design and evaluation of visual representations to better support controllers’ analytical capabilities and decision-making. Four novel visual analytics interfaces were designed, developed, and tested over the course of this research project. To understand how the designed visual representations affected the operators’ decision-making processes, evaluation studies with air traffic controllers as well as novices without ATC experience were conducted for two of the designed interfaces and the results were analyzed. 

    The contribution of this thesis to the field of air traffic control and visualization design is fourfold. First, the thesis contributes knowledge on what information should be visualized and how, to achieve functional goals of conflict detection and resolution task of air traffic control. Second, evolved through a series of design studies, a final interactive visual analytics interface is proposed that visualizes information about the available solution space for solving conflict situations between airborne traffic and the traffic complexity. The interface supports controllers’ decision-making process for resolving conflicts and ability to reduce the traffic complexity. Third, the method developed for evaluating the interface designs contribute with knowledge on how interfaces tailored to safety-critical systems can be tested. Fourth, findings show that the integration of ecological interface design with the development of visual representations can shape novice and expert operators’ decision-making towards domain-specific functional goals, while allowing them to follow their own problem-solving strategies. 

    List of papers
    1. Design of a Real Time Visual Analytics Support Tool for Conflict Detection and Resolution in Air Traffic Control
    Open this publication in new window or tab >>Design of a Real Time Visual Analytics Support Tool for Conflict Detection and Resolution in Air Traffic Control
    2020 (English)In: EuroVis 2020 - Short Papers, Eurographics - European Association for Computer Graphics, 2020Conference paper, Published paper (Refereed)
    Abstract [en]

    Air traffic control is a safety critical high-risk environment where operators need to analyse and interpret traffic dynamics of spatio-temporal data in real-time. To support the air traffic controller in safely separating traffic, earlier research has applied real-time visualisation techniques that explore the constraints and solution spaces of separation problems. Traditionally, situation displays for conflict detection and resolution have used visualisations that convey information about the relative horizontal position between aircraft. Although vertical solutions for solving conflicts are common, and often a preferred among controllers, visualisations typically provide limited information about the vertical relationship between aircraft. This paper presents a design study of an interactive conflict detection and resolution support tool and explores techniques for real-time visualisation of spatio-temporal data. The design evolution has incorporated several activities, including an initial work domain analysis, iterative rounds of programming, design, and evaluations with a domain expert, and an evaluation with eight active controllers. The heading-time-altitude visualisation system is developed based on formulating and solving aircraft movements in a relative coordinate system. A polar-graph visualisation technique is used to construct a view of conflicting aircraft vertical solution spaces in the temporal domain. Using composite glyphs, the final heading-time-altitude visualisation provides a graphical representation of both horizontal and vertical solution spaces for the traffic situation.

    Place, publisher, year, edition, pages
    Eurographics - European Association for Computer Graphics, 2020
    National Category
    Media and Communication Technology
    Identifiers
    urn:nbn:se:liu:diva-179234 (URN)10.2312/evs.20201044 (DOI)
    Conference
    EuroVis, Norrköping, Sweden, May 25-29, 2020
    Funder
    Swedish Research Council
    Available from: 2021-09-14 Created: 2021-09-14 Last updated: 2022-09-14Bibliographically approved
    2. Design and Evaluation Study of Visual Analytics Decision Support Tools in Air Traffic Control
    Open this publication in new window or tab >>Design and Evaluation Study of Visual Analytics Decision Support Tools in Air Traffic Control
    2022 (English)In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 41, no 1, p. 230-242Article in journal (Refereed) Published
    Abstract [en]

    Operators in air traffic control facing time- and safety-critical situations call for efficient, reliable and robust real-time processing and interpretation of complex data. Automation support tools aid controllers in these processes to prevent separation losses between aircraft. Issues of current support tools include limited what-if and what-else probe functionalities in relation to vertical solutions. This work presents the design and evaluation of two visual analytics interfaces that promote contextual awareness and support what-if and what-else probes in the spatio-temporal domain aiming to improve information integration and support controllers in prioritising conflict resolution. Both interfaces visualize vertical solution spaces against a time-altitude graph. The main contributions of this paper are: (a) the presentation of two interfaces for supporting conflict solving; (b) the novel representation of how vertical information and aircraft rate of climb and descent affect conflicts and (c) an evaluation and comparison of the interfaces with a traditional air traffic control support system. The evaluation study was performed with domain experts to compare the effects of visualization concepts on operator engagement in processing solutions suggested by the tools. Results show that the visualizations support operators ability to understand and resolve conflicts. Based on the results, general design guidelines for time-critical domains are proposed.

    Place, publisher, year, edition, pages
    Wiley, 2022
    Keywords
    Human-computer interfaces; interaction; information visualization; visual analytics; visualization
    National Category
    Human Computer Interaction
    Identifiers
    urn:nbn:se:liu:diva-182019 (URN)10.1111/cgf.14431 (DOI)000729763500001 ()
    Available from: 2022-01-03 Created: 2022-01-03 Last updated: 2022-10-27
    3. Exploring Effects of Ecological Visual Analytics Interfaces on Experts' and Novices' Decision‐Making Processes: A Case Study in Air Traffic Control
    Open this publication in new window or tab >>Exploring Effects of Ecological Visual Analytics Interfaces on Experts' and Novices' Decision‐Making Processes: A Case Study in Air Traffic Control
    2022 (English)In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 41, no 3, p. 453-464Article in journal (Refereed) Published
    Abstract [en]

    Operational demands in safety-critical systems impose a risk of failure to the operators especially during urgent situations. Operators of safety-critical systems learn to make decisions effectively throughout extensive training programs and many years of experience. In the domain of air traffic control, expensive training with high dropout rates calls for research to enhance novices' ability to detect and resolve conflicts in the airspace. While previous researchers have mostly focused on redesigning training instructions and programs, the current paper explores possible benefits of novel visual representations to improve novices' understanding of the situations as well as their decision-making process. We conduct an experimental evaluation study testing two ecological visual analytics interfaces, developed in a previous study, as support systems to facilitate novice decision-making. The main contribution of this paper is threefold. First, we describe the application of an ecological interface design approach to the development of two visual analytics interfaces. Second, we perform a human-in-the-loop experiment with forty-five novices within a simplified air traffic control simulation environment. Third, by performing an expert-novice comparison we investigate the extent to which effects of the proposed interfaces can be attributed to the subjects' expertise. The results show that the proposed ecological visual analytics interfaces improved novices' understanding of the information about conflicts as well as their problem-solving performance. Further, the results show that the beneficial effects of the proposed interfaces were more attributable to the visual representations than the users' expertise. 

    Place, publisher, year, edition, pages
    Chichester, United Kingdom: Wiley-Blackwell Publishing Inc., 2022
    National Category
    Human Computer Interaction
    Identifiers
    urn:nbn:se:liu:diva-187151 (URN)10.1111/cgf.14554 (DOI)000842261500039 ()
    Conference
    24th Eurographics/IEEE VGTC Conference on Visualization (EuroVis), Rome, ITALY, jun 12-17, 2022
    Note

    Funding: KAW Scholar Grant

    Available from: 2022-08-08 Created: 2022-08-08 Last updated: 2022-09-27Bibliographically approved
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  • 1590.
    Zohrevandi, Elmira
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Visualization of Complex Situations to Strengthen Human-Automation Collaboration2019In: PROCEEDINGS OF THE 31ST EUROPEAN CONFERENCE ON COGNITIVE ERGONOMICS: DESIGN FOR COGNITION (ECCE 2019), ASSOC COMPUTING MACHINERY , 2019, p. 14-18Conference paper (Refereed)
    Abstract [en]

    Automation in todays world has helped human operators accomplish several tasks in limited time. Therefore, humans role in automated environments are shifting from operational tasks to supervisory tasks. In complex environments such as air traffic control, supervisory tasks become difficult to manage during unforeseen situations as the controller needs to have a clear understanding of different operational levels in the system and make decisions about them in a limited amount of time. For the operators working with highly complex information-rich automated systems, an improper way of presenting the information would waste operators cognitive resources resulting in inefficient decision making and increase in risk of failure. In this research proposal goals and plans are described for doing research on design and visualization of information specifically applied to high stake automated environments. The research project initially addresses the problem in the domain of air traffic control. The contribution of the project to the field so far has been design and development of an interactive tool, which visualizes the information about conflict solution space to facilitate decision making process. The research project is planned to be completed over the course of a four-year PhD studies.

  • 1591.
    Zohrevandi, Elmira
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Brorsson, Emmanuel
    ABB, Sweden.
    Darnell, Andreas
    Södra Cell, Sweden.
    Bång, Magnus
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Design of an Ecological Visual Analytics Interface for Operators of Time-Constant Processes2023In: 2023 IEEE Visualization and Visual Analytics (VIS), IEEE, 2023, p. 131-135Conference paper (Refereed)
    Abstract [en]

    In industrial applications where the physical parameters are highly interconnected, keeping the process flow steady is a major concern for the operators. This is caused by the sensitivity of system to the process dynamics. As a result, a slight adjustment to a control parameter can significantly affect the efficiency of the system and thus impact the financial gain. Paper pulp production is an example of such a process, where operators continuously investigate the potential of changes in the process and predict the consequences of an adjustment before making a decision. Process parameter adjustments prescribed by simulated control models cannot be fully trusted as the external disturbances and the process inherent variabilities cannot be fully incorporated into the simulations. Therefore, to assess the viability of a strategy, operators often compare the situation with the historical records and trends during which the processes in the plant ran steadily. While previous research has mostly focused on developing advanced control models to simulate complex pulp production process, this work aims to support operators analytical reasoning by provision of effective data visualization. The contributions of our design study include a domain problem characterization and a linked-view visual encoding design, which aims to enhance operator's mental models independent of particular users or scenarios. Finally, by reflecting on the advantages of our choice of task abstraction technique, inherited from the ecological interface design framework [5], we reason for the generalizability of our approach to similar industrial applications.

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  • 1592.
    Zohrevandi, Elmira
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Svensson, Åsa
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Johansson, Jimmy
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Josefsson, Billy
    Air Navigation Services of Sweden (LFV) Norrköping, Sweden.
    Modeling and Analysis of Controller’s Taskload in Different Predictability Conditions2016Conference paper (Refereed)
    Abstract [en]

    This study aims to first develop a successful taskloadmodel which is able to relate the controller’s interaction with theradar screen to the dynamical changes in air traffic patterns.Secondly, the study aims to examine whether i4D equipage, as aspecific notion of automation, contributes to an improvement inquantification of controller’s taskload model. Thirdly, in a morespecific approach the study intends to analyze to what extentcontrollers may or may not benefit from predictable situations atdense traffic conditions when exposed to higher automatedairspace environment. The model is applied on 18 data setsfeaturing different i4D-equipage levels. It compares controllers’taskload for three different scenarios between an en-route and aterminal sector. 

  • 1593.
    Zohrevandi, Elmira
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Westin, Carl
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Design and Evaluation Study of Visual Analytics Decision Support Tools in Air Traffic Control2022In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 41, no 1, p. 230-242Article in journal (Refereed)
    Abstract [en]

    Operators in air traffic control facing time- and safety-critical situations call for efficient, reliable and robust real-time processing and interpretation of complex data. Automation support tools aid controllers in these processes to prevent separation losses between aircraft. Issues of current support tools include limited what-if and what-else probe functionalities in relation to vertical solutions. This work presents the design and evaluation of two visual analytics interfaces that promote contextual awareness and support what-if and what-else probes in the spatio-temporal domain aiming to improve information integration and support controllers in prioritising conflict resolution. Both interfaces visualize vertical solution spaces against a time-altitude graph. The main contributions of this paper are: (a) the presentation of two interfaces for supporting conflict solving; (b) the novel representation of how vertical information and aircraft rate of climb and descent affect conflicts and (c) an evaluation and comparison of the interfaces with a traditional air traffic control support system. The evaluation study was performed with domain experts to compare the effects of visualization concepts on operator engagement in processing solutions suggested by the tools. Results show that the visualizations support operators ability to understand and resolve conflicts. Based on the results, general design guidelines for time-critical domains are proposed.

    Download full text (pdf)
    fulltext
  • 1594.
    Zohrevandi, Elmira
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Westin, Carl
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Design of a Real Time Visual Analytics Support Tool for Conflict Detection and Resolution in Air Traffic Control2020In: EuroVis 2020 - Short Papers, Eurographics - European Association for Computer Graphics, 2020Conference paper (Refereed)
    Abstract [en]

    Air traffic control is a safety critical high-risk environment where operators need to analyse and interpret traffic dynamics of spatio-temporal data in real-time. To support the air traffic controller in safely separating traffic, earlier research has applied real-time visualisation techniques that explore the constraints and solution spaces of separation problems. Traditionally, situation displays for conflict detection and resolution have used visualisations that convey information about the relative horizontal position between aircraft. Although vertical solutions for solving conflicts are common, and often a preferred among controllers, visualisations typically provide limited information about the vertical relationship between aircraft. This paper presents a design study of an interactive conflict detection and resolution support tool and explores techniques for real-time visualisation of spatio-temporal data. The design evolution has incorporated several activities, including an initial work domain analysis, iterative rounds of programming, design, and evaluations with a domain expert, and an evaluation with eight active controllers. The heading-time-altitude visualisation system is developed based on formulating and solving aircraft movements in a relative coordinate system. A polar-graph visualisation technique is used to construct a view of conflicting aircraft vertical solution spaces in the temporal domain. Using composite glyphs, the final heading-time-altitude visualisation provides a graphical representation of both horizontal and vertical solution spaces for the traffic situation.

  • 1595.
    Zohrevandi, Elmira
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Westin, Carl
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Vrotsou, Katerina
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Exploring Effects of Ecological Visual Analytics Interfaces on Experts' and Novices' Decision‐Making Processes: A Case Study in Air Traffic Control2022In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 41, no 3, p. 453-464Article in journal (Refereed)
    Abstract [en]

    Operational demands in safety-critical systems impose a risk of failure to the operators especially during urgent situations. Operators of safety-critical systems learn to make decisions effectively throughout extensive training programs and many years of experience. In the domain of air traffic control, expensive training with high dropout rates calls for research to enhance novices' ability to detect and resolve conflicts in the airspace. While previous researchers have mostly focused on redesigning training instructions and programs, the current paper explores possible benefits of novel visual representations to improve novices' understanding of the situations as well as their decision-making process. We conduct an experimental evaluation study testing two ecological visual analytics interfaces, developed in a previous study, as support systems to facilitate novice decision-making. The main contribution of this paper is threefold. First, we describe the application of an ecological interface design approach to the development of two visual analytics interfaces. Second, we perform a human-in-the-loop experiment with forty-five novices within a simplified air traffic control simulation environment. Third, by performing an expert-novice comparison we investigate the extent to which effects of the proposed interfaces can be attributed to the subjects' expertise. The results show that the proposed ecological visual analytics interfaces improved novices' understanding of the information about conflicts as well as their problem-solving performance. Further, the results show that the beneficial effects of the proposed interfaces were more attributable to the visual representations than the users' expertise. 

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  • 1596.
    Zuo, Guangzheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Linares, Mathieu
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Upreti, Tanvi
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    General rule for the energy of water-induced traps in organic semiconductors2019In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 18, no 6, p. 588-+Article in journal (Refereed)
    Abstract [en]

    Charge carrier traps are generally highly detrimental for the performance of semiconductor devices. Unlike the situation for inorganic semiconductors, detailed knowledge about the characteristics and causes of traps in organic semiconductors is still very limited. Here, we accurately determine hole and electron trap energies for a wide range of organic semiconductors in thin-film form. We find that electron and hole trap energies follow a similar empirical rule and lie similar to 0.3-0.4 eV above the highest occupied molecular orbital and below the lowest unoccupied molecular orbital, respectively. Combining experimental and theoretical methods, the origin of the traps is shown to be a dielectric effect of water penetrating nanovoids in the organic semiconductor thin film. We also propose a solvent-annealing method to remove water-related traps from the materials investigated, irrespective of their energy levels. These findings represent a step towards the realization of trap-free organic semiconductor thin films.

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  • 1597.
    Ärnekvist, Sanna
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    A study of principles for increasing sales with packaging design as a tool2014Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Detta arbete handlar om hur konsumenter påverkas av förpackningslayout och möjligheten att använda det som verktyg för få produkter att sälja mer. Resonemanget vilar bland annat på teorier om hur kunder påverkas socialt och kulturellt och vad som gör en förpackningslayout trovärdig på så sätt att en kund skulle vilja köpa den. Arbetet tar även upp möjligheter att använda förpackningar i marknadsföring och hur stor roll varumärket har för försäljningen. Studierna i form av gruppintervju, enkätundersökning och mailintervju bekräftar till stora delar det som nämns i teoriavsnittet. Metoderna analyseras och slutsatser dras, i diskussionen visas en om-design för en produkt grundat på de analyser och slutsatser som tagits. Resultatet säger att en tilltalande, enkel och trovärdig förpackning med tydlig information och med färger som förknippas med innehållet ökar försäljningen av en produkt.

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  • 1598.
    Ågren, Hannah
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Utformning av en applikation för att reducera stress kopplat till hem och hushåll2022Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This report examines how a Hi-Fi prototype of a mobile application can be developed to reduce stress for women, in the age span of 26-41, with children. Where stress is related to home and household. Home and household in this thesis relates to all kinds of chores or tasks executed in the home. This includes tasks such as cooking, planning of family activities and organization of tasks. The goal is to examine how a HiFi prototype, of an application, can be designed to ease the tasks of household planning and help reduce stress for the mothers in the family. The work has been executed in a design process with the user in focus, a method established by Arvola, along with a pilot study that has produced the target group and their need for certain functions in the application. By doing a pilot study, user tests and interviews, the work has been evaluated and resulted in a Hi-Fi prototype called Plannie.The results from the user tests and interview showed that the Hi-Fi prototype met the defined goals and fulfilled the criterion. It also showed that its functions and interface provided a good user experience for the target group. The Hi-Fi prototype also showed potential for development, either as a prototype or a real application, since a need for support amongst the target group could be established.

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  • 1599.
    Åkerman, Linda
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Kommunikation i Norrköpings kommun - En fallstudie av krisen under Bråvalla Festival 20142017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Idag lever vi i ett digitalt samhälle där det tidvis uppdagas kriser av olika slag. På grund av att medborgare jämt och ständigt kan bevaka, sprida och dela information med varandra, har allt fler kommuner valt att arbeta med sociala medier vid kris. Denna studie syftar därför till att kartlägga hur en svensk kommun arbetar med Facebook i sitt kriskommunikationsarbete. Studien visar att en kommuns syfte med att i kristider finnas på Facebook kan vara att snabbt nå ut till intressenter med krisinformation. En kommun måste inte nödvändigtvis kommunicera med en specifikt uttalad målgrupp via kanalen utan kan istället där försöka nå så många intressenter som möjligt. Före en kris kan en kommun publicera Facebookinlägg som är av varnande och uppmanande karaktär. En kommun kan också arbeta aktivt med att förebygga kriser. Under en kris kan en kommun publicera Facebookinlägg av instruerande karaktär för att lugna intressenter. En kommun kan under en kris också försöka förhindra ryktesspridning genom att själv se till att vara aktiv och ständigt gå ut med trovärdig information. Efter en kris kan en kommun publicera Facebookinlägg för att ge så kallad övrig information till intressenter. En kommun kan också dra flera lärdomar av en avklarad kris. Ett exempel på en sådan är att sociala medier öppnar upp för så snabb kriskommunikation att de interna riktlinjerna inte alltid räcker till. Avslutningsvis finner studien flera fördelar och nackdelar med att som kommun arbeta med kriskommunikation på Facebook.

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    Communication before, during and after a crisis in Norrköping municipality - A case study of the crisis in Bråvalla Festival 201
  • 1600.
    Åkesson, Malin
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Partti, Eliin
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Färg på tidskriftsomslag: En studie om färgers betydelse på Cosmopolitans omslag2012Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    A consumer is constantly influenced by the different impressions in a store where products compete for attention and try to differentiate themselves from competitors. A product that is crowded with several others on store shelves is magazines, and number of titles on the Swedish market have increased by 40 per cent over the past ten years. 

    Previous studies show how colors are said to influence people in different situations, that red, for example, is a good color to attract a consumer. This does not necessarily mean that it leads to a purchase. What is it that interests the consumer in terms of color? What colors on a magazine cover is of interest to an audience, most and least, and why is it so? Is there a connection between the colors that interest the target audience and the colors that actually lead to purchases?This study examines how the color of the magazine cover affects a consumer, both in terms of associations, emotions and buying needs. The magazine that has been in focus of the study is Cosmopolitan, targeting women aged 20-30 years, which is within the genre of Lifestyle for women. The study includes a literature review to learn more about how color affects a consumer’s attention and what value a certain color has. Furthermore, sketches had been created that has been the foundation of the focus groups who were assembled.The analysis made shows that the audience liked the following colors and color combinations on a Cosmopolitan cover: blue, yellow, cold and bright colors. The covers that made the audience most interested in a purchase had the following color and color combinations: blue, yellow, blue-yellow, cold and bright colors. This shows that the study found a correlation between the colors that audience liked best with the colors that the target group also could consider buying.The colors that audience did not like was the following colors and color combinations: black, red-green, blue-red, green, green-yellow and warm colors. The covers that the target group found least interesting to buy were the following colors and color combinations: red, green, blue-red, red-green and green-yellow. The covers that the target group found most interesting was the following colors and color combinations: red, blue-red, green, green-yellow, and warm and dark covers. What appears in the study is that the use of red on the magazine cover captures the consumer’s interest but it would not lead to purchase, according to the focus groups for this study. It is also clear that the colors that are considered to be most interesting is not in the target audience like or choose to buy. Another finding was that the target audience often choose what was most familiar to them.

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    Färg på tidskriftsomslag
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