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  • 1.
    Andrée, Martin
    et al.
    Lantmäteriet.
    Larsson, Karolina
    KLM; Stockholms stad.
    Nordqvist Darell, Fanny
    Stockholms stad.
    Malm, Linus
    Tyréns.
    Tullberg, Odd
    WSP.
    Wallberg, Ann
    JM.
    Norsell, Johan
    NAI Svefa.
    Paasch, Jesper M.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Paulsson, Jenny
    Kungliga Tekniska Högskolan, Stockholm.
    Slutrapport för projektet Smart planering för byggande: Delprojekt 3 - BIM som informationsstöd för 3D fastighetsbildning2018Rapport (Annet vitenskapelig)
    Abstract [sv]

    Samhällsbyggnadsprocessen behöver utvecklas och bli smartare, öppnare och mer effektiv för ett ökat bostadsbyggande. En digitalisering av samhällsbyggnadsprocessen kan ge ett effektivare samarbete mellan kommun, fastighetsägare, byggherrar, medborgare, näringsliv och myndigheter.Vid bildande av tredimensionellt avgränsade fastigheter eller fastighetsutrymmen (3D-fastigheter) behöver gränsernas läge redovisas både verbalt och i kartor och ritningar, detsamma gäller berörda rättigheter. Det är idag ofta svårt att korrekt redovisa en 3D-volym med enbart dagens pappersritningar och även svårt att läsa en registerkarta i 2D med fastigheter och rättigheter beslutade i 3D. Beslutsunderlagen i fastighetsbildnings-processen behöver bli mer enhetliga och entydiga samt fastighetsinformationen behöver bli återanvändningsbar i hela samhällsbyggnadsprocessen.I detta projekt har vi studerat informationsbehovet i de olika tidpunkterna under fastighetsbildningsprocessen för 3D-fastigheter med fokus på vem som är ansvarig för att tillhandahålla informationsunderlag för att identifiera krav på utformning av 3D-modeller (t.ex BIM) och 3D-stöd för fastighetsbildning.Internationellt finns det ett stort intresse och många frågeställningar gällande samspelet mellan BIM och Fastighetsinformation; det är däremot ganska få fall som har identifierats där man har arbetat praktiskt med BIM i relation till redovisning av 3D-fastigheter.Projektethar även tittat på behov av visualisering och tillhandahållande av fastighetsinformation i 3D, hur informationen bör utformas för att kunna tolkas korrekt samt nyttjas vidare av andra aktörer i samhällsbyggnadsprocessen.Slutsatsen i projektetär att en framtida arbetsmodell där man i samband med myndighetsutövningen för fastighetsbildning samverkar med stöd av BIM och geografisk information i ärendehandläggningen kan ge stora effekter på både myndighetens effektivitet och i ärendeutövningen och för förståelsen av fastighetbildningsbeslutet hos samtliga intressenter i processen. För att det arbete som genomförts i denna utredning skall få genomslag i den dagliga verksamheten rekommenderar vibland annatatt de statliga och kommunala lantmäterimyndigheterna arbetar vidare med att utveckla arbetsprocessen och rekommendationerna för 3D-fastighetsbildning baserat på resultatet från detta projekt och redan i dagens modell efterfrågar att man i handläggningsprocessen kan arbeta BIM-baserat även om kommande beslutshandlingar under en övergångsperiod fortfarande kommer att vara baserade på ritningsbilagor i 2D.

  • 2.
    Andrée, Martin
    et al.
    Lantmäteriet.
    Paasch, Jesper M.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Paulsson, Jenny
    Kungliga Tekniska Högskolan.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    BIM and 3D property visualisation2018Inngår i: FIG Congress 2018: Proceedings, 2018, artikkel-id 9367Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The concept of 3D property has only existed a short period of time in Sweden, being introduced in 2004 and expanded in 2009 by the addition of condominium (apartment) ownership. It is therefore a rather new form of land management, and the demand for 3D property formation has not been as high as initially expected. There is however an increased interest in 3D property and ownership apartments today, also as being part of the nation’s geospatial infrastructure together with related 3D information for e.g. buildings, utility networks and other features. An effective management of 3D property is depending on, among other things, visualization, representation and storage of 3D real property data, such as legal boundaries and real property rights. There are at present a number of ongoing 3D development and research projects focusing on visualization and standardization of 3D cadastral boundaries. They are part of the national "Smart Built Environment" development and research program, which includes the use of BIM in the (future) 3D property formation process with focus on visualization of 3D real property and condominiums, and specification of requirements and evaluation of 3D digital real property information created and managed in the processes.

    This paper presents the preliminary results of the working group on visualization of 3D boundaries in the project "Smart planning, construction and management processes throughout the life cycle". The aim is to test the results produced in the project "Information for planning, real property formation and building permission", working group "BIM for 3D property formation." The purpose of this working group is to set the requirements for and evaluate the test bed for 3D property information. The focus is on visualization of 3D property and ownership apartments. The proposed model for digitization and visualization of 3D property formation will be tested in a test bed environment. A pilot case from the Stockholm area is then used in the test bed to see how it could work in practice.

    The expected outcome is recommendations for the exchange of documentation and other digital information in 3D processes, the visualization of legal boundaries for stakeholders, registration of legal 3D objects in the Swedish national real property register and how to communicate 3D models to right holders/stakeholders for 3D property and condominiums and the property market, as well as suggestions for a homogeneous, effective and digital flow of 3D information to be used by actors and other stakeholders in the property formation, planning and building processes.

  • 3.
    Aslani, Mohammad
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Faculty of Geodesy and Geomatics Engineering, K.N. Toosi University of Technology, Tehran, Iran.
    Mohammad Saadi, Mesgari
    Division of Visual Information and Interaction, Department of Information Technology, Uppsala University, Uppsala, Sweden.
    Wiering, Marco A.
    Institute of Artificial Intelligence and Cognitive Engineering, University of Groningen, Groningen, Netherlands.
    Traffic signal optimization through discrete and continuous reinforcement learning with robustness analysis in downtown Tehran2018Inngår i: Advanced Engineering Informatics, ISSN 1474-0346, E-ISSN 1873-5320, Vol. 38, s. 639-655Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Traffic signal control plays a pivotal role in reducing traffic congestion. Traffic signals cannot be adequately controlled with conventional methods due to the high variations and complexity in traffic environments. In recent years, reinforcement learning (RL) has shown great potential for traffic signal control because of its high adaptability, flexibility, and scalability. However, designing RL-embedded traffic signal controllers (RLTSCs) for traffic systems with a high degree of realism is faced with several challenges, among others system disturbances and large state-action spaces are considered in this research.

    The contribution of the present work is founded on three features: (a) evaluating the robustness of different RLTSCs against system disturbances including incidents, jaywalking, and sensor noise, (b) handling a high-dimensional state-action space by both employing different continuous state RL algorithms and reducing the state-action space in order to improve the performance and learning speed of the system, and (c) presenting a detailed empirical study of traffic signals control of downtown Tehran through seven RL algorithms: discrete state Q-learning(λ" role="presentation">), SARSA(λ" role="presentation">), actor-critic(λ" role="presentation">), continuous state Q-learning(λ" role="presentation">), SARSA(λ" role="presentation">), actor-critic(λ" role="presentation">), and residual actor-critic(λ" role="presentation">).

    In this research, first a real-world microscopic traffic simulation of downtown Tehran is carried out, then four experiments are performed in order to find the best RLTSC with convincing robustness and strong performance. The results reveal that the RLTSC based on continuous state actor-critic(λ" role="presentation">) has the best performance. In addition, it is found that the best RLTSC leads to saving average travel time by 22% (at the presence of high system disturbances) when it is compared with an optimized fixed-time controller.

  • 4.
    Ericsson, Martin
    et al.
    Uppsala universitet.
    Hast, Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    A Heterogeneous Cluster framework for Computationally Heavy Visualizations2009Inngår i: Proceedings of IADIS Applied Computing 2009, 2009, s. 337-339Konferansepaper (Fagfellevurdert)
  • 5.
    Forsberg, Ann-Kristin
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Winkler Pettersson, Lars
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Linden, Elisabet
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för inomhusmiljö.
    Sandberg, Mats
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för inomhusmiljö.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    An augmented-reality approach to co-located visual exploration of indoor climate data in real rooms2005Inngår i: Indoor Air 2005: Proceedings of the 10th International Conference on Indoor Air Quality and Climate, 2005, s. 2860-2860Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We live in two spaces, the visible space and the non-visible but otherwise sensed space. Both spaces must satisfy our needs and there is a relation between them. If parts of the room are too cold this will lead to a restriction of the use of the room. We cannot endure draft for any longer time. Draft caused by a ventilation supply frequently leads to blockage of the supply device, which in turn gives rise to a reduction of the ventilation rate. The final result may be a deterioration of the air quality. Therefore, to be able to guarantee the air quality it is necessary to make the invisible thermal climate visible. In this paper a novel method based on Augmented Reality for presenting die thermal climate is presented and discussed. The data, e.g. temperatures and velocities, are shown on a lightweight display. Several people can walk around in a real room and see on a screen where the hot and/or cold spots may appear. Different ventilation solutions could in that way be compared in a dialogue between different actors in the building process.

  • 6. Forsell, C
    et al.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Lind, M
    Simple 3D Glyphs for Spatial Multivariate Data2005Inngår i: Proceedings of the IEEE Symposium on Information Visualization – Infovis 2005, 2005, s. 119-124Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We present an effort to evaluate the possible utility of a new type of 3D glyphs intended for visualizations of multivariate spatial data. They are based on results from vision research suggesting that our perception of metric 3D structure is distorted and imprecise relative to the actual scene before us (e.g., [1]); only a class of qualitative properties of the scene is perceived with accuracy. These properties are best characterized as being invariant over affine but not Euclidean transformations. They are related, but not identical to, the non-accidental properties (NAPs) described by Lowe [2] on which the notion of geons is based [3]. A large number of possible 3D glyphs for the visualization of spatial data can be constructed using such properties. One group is based on the local sign of surface curvature. We investigated these properties in a visualization experiment. The results are promising and the implications for visualization are discussed.

  • 7. Forsell, C.
    et al.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Lind, M.
    Surface Glyphs for Efficient Visualization of Multivariate Data2006Inngår i: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 5, nr 2, s. 112-124Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a first effort to evaluate the possible utility of a new type of surface glyphs intended for visualizations of multivariate spatial data. The glyphs are based on results from vision research suggesting that our perception of metric 3D structure is distorted and imprecise relative to the actual scene before us; only a class of qualitative properties of the scene is perceived with accuracy. These properties are best characterized as being invariant over affine but not Euclidean transformations. A large number of possible 3D glyphs for the visualization of spatial data can be constructed using such properties. One group of such glyphs is based on the local sign of surface curvature. We investigated this group in two visualization experiments. The results show that available sources of 3D structural information were sufficient for our subjects to make fast and accurate judgments. Some implications for visualization are also discussed.

  • 8.
    Hast, Anders
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Ericsson, Martin
    UPPMAX, Uppsala University, Uppsala, Sweden .
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Multiscale Texture Synthesis and Colourization of Greyscale Textures2010Inngår i: 18th International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision, WSCG 2010 - In Co-operation with EUROGRAPHICS: Full Papers Proceedings, Plzen: Union Agency Science Press , 2010, s. 55-61Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main idea presented herein is to use a multiscale texture synthesis approach in order to both colourize and upscale greyscale textures. Such textures can be vintage photos to be used in archaeological or urban 3D visualizations and obviously the colour needs to be reconstructed some way. Due to limited quality, walls etc in such 3D visualizations will appear either pixelized or blurry when the viewer approaches them on a close distance. The latter if some kind of interpolation technique is being used to reduce the pixelization. The low resolution greyscale texture and a high resolution coloured texture is used for the colourization and upscaling, which will produce a colour version of the greyscale texture with 4 times higher resolution in each upscale step. The novel idea is to use multiscale texture synthesis in HSV space for the first upscale in order to create a RGB colour image for subsequent upscaling, using either ordinary RGB multiscale texture synthesis or continue using HSV multiscale texture synthesis. These two main approaches will be compared and discussed.

  • 9.
    Hast, Anders
    et al.
    Uppsala universitet.
    Jenke, Peter
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Uppsala universitet.
    Shortest diagonal triangulation of convex layers2013Inngår i: Proceedings of the IASTED International Conference on Signal Processing, Pattern Recognition and Applications, SPPRA 2013, 2013, s. 424-430Konferansepaper (Fagfellevurdert)
    Abstract [en]

    One problem in the field of computational geometry is the triangulation of convex layers. The rotating caliper algorithm is an alternative to the constrained Delaunay triangulation method. We present an improved triangulation algorithm, which gives a mesh quality close to that of the Constrained Delaunay but substantially faster. Each layer will be connected to the neighboring layer by edges and from the two vertices constituting an edge the proposed algorithm will select the shortest diagonal to its next neighbors in the polygonal chain on the other side, i.e. from the outer layer to the inner layer or vice versa. We discuss quality issues regarding the rotating caliper method and some improvements to it, as well as how a Constrained Delaunay can be efficiently implemented for convex layers.

  • 10.
    Hast, Anders
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Wesslén, Daniel
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Improved Diffuse Anisotropic Shading2004Inngår i: Proceedings of the Annual SIGRAD Conference, 2004, s. 57-58Konferansepaper (Fagfellevurdert)
  • 11.
    Jenke, Peter
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Hast, Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    On the quality of point-cloud triangulations based on convex hulls2010Inngår i: Proceedings of the Annual SIGRAD Conference 2010, 2010, s. 71-76Konferansepaper (Fagfellevurdert)
  • 12. Jensen, N
    et al.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Nejdl, W
    Olbrich, S
    CoVASE - Collaborative Visualization for Constructivist Learning2003Inngår i: Designing for Change in Networked Learning Environments, 2003, s. 249-253Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The paper specifies CoVASE, a software for teachers to create and view networked learning environments (VE). Students carry out virtual experiments in CoVASE, at the same time and from different places. They use the same tools and work on the same scientific problems as researchers do. Teachers create a motivating, demanding, and authentic interaction between learners and real-world problems, a premise for constructivist learning (CL). CoVASE generates and displays the result of a numerical simulation in parallel of its progress on distributed 3D graphic viewers, steered by users in real-time. VEs mediate communication between users, deictic elements, and display. Researchers and students have evaluated the predecessors of CoVASE with good results. A field study is planned for 2003.

  • 13. Jensen, N
    et al.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    von Voigt, G
    Raasch, S
    Olbrich, S
    Nejdl, W
    Development of a Virtual Laboratory System for Science Education and the Study of Collaborative Action2004Inngår i: Proceedings of AACE ED Media Conference 2004, 2004Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The paper specifies the development of a toolkit to run synthetic science laboratories. The aim was to facilitate collaborative experimenting for problem-based learning in a virtual lab. The goal was to demonstrate virtual experimenting by use of interactive 3D visualization and simulation. Technology was developed over six years and in part designed in explicit accordance to didactic models. For tests, we built a virtual lab that comprised media tools and complex computer simulations, and we evaluated it with promising results. Students used data from meteorology and experimented together. Generally, they enjoyed using the system and collaborated in a motivated way. We identified which tools they preferred. The paper indicates ways to improve the design of virtual labs by use of our toolkit.

  • 14.
    Kjellin, Andreas
    et al.
    Uppsala University.
    Pettersson, Lars Winkler
    Uppsala university.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Lind, Mats
    Uppsala University.
    Evaluating 2D and 3D Visualizations of Spatiotemporal Information2010Inngår i: ACM Transactions on Applied Perception, ISSN 1544-3558, E-ISSN 1544-3965, Vol. 7, nr 3, s. 19:1-19:23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Time-varying geospatial data presents some specific challenges for visualization. Here, we report the results of three experiments aiming at evaluating the relative efficiency of three existing visualization techniques for a class of such data. The class chosen was that of object movement, especially the movements of vehicles in a fictitious landscape. Two different tasks were also chosen. One was to predict where three vehicles will meet in the future given a visualization of their past movement history. The second task was to estimate the order in which four vehicles arrived at a specific place. Our results reveal that previous findings had generalized human perception in these situations and that large differences in user efficiency exist for a given task between different types of visualizations depicting the same data. Furthermore, our results are in line with earlier general findings on the nature of human perception of both object shape and scene changes. Finally, the need for new taxonomies of data and tasks based on results from perception research is discussed.

  • 15.
    Kjellin, Andreas
    et al.
    Informationsvetenskap, Uppsala universitet.
    Winkler Pettersson, Lars
    Informationsteknologi, Uppsala universitet.
    Seipel, Stefan
    Informationsvetenskap, Uppsala universitet.
    Lind, Mats
    Informationsvetenskap, Uppsala universitet.
    Different levels of 3D: an evaluation of visualized discrete spatiotemporal data in space-time cubes2010Inngår i: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 9, nr 2, s. 152-164Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    New technologies and techniques allow novel kinds of visualizations and different types of 3D visualizations are constantly developed. We propose a categorization of 3D visualizations and, based on this categorization, evaluate two versions of a space-time cube that show discrete spatiotemporal data. The two visualization techniques used are a head-tracked stereoscopic visualization ('strong 3D') and a static monocular visualization ('weak 3D'). In terms of effectiveness and efficiency the weak 3D visualization is as good as the strong 3D and thus the need for advanced 3D visualizations in these kinds of tasks may not be necessary.

  • 16.
    Koch, Sabine
    et al.
    CMD Center for Human - Computer Studies , Uppsala University, Uppsala, Sweden.
    Wagner, Ina-Veronika
    CMD Center for Human - Computer Studies , Uppsala University, Uppsala, Sweden.
    Seipel, Stefan
    CMD Center for Human - Computer Studies , Uppsala University, Uppsala, Sweden.
    Schneider, Werner
    CMD Center for Human - Computer Studies , Uppsala University, Uppsala, Sweden.
    Controlled Diagnosis-Oriented Enhancement of Automatically Segmented Radiographs in Dentistry1998Inngår i: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 57, nr 1-2, s. 125-131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for controlled diagnosis-oriented enhancement of selected regions of interest in intraoral radiographs is presented. Image enhancement is accomplished by adaptive non-linear grey scale transformation depending on the result of objective quality measurement. In order to assure reliable image duality measurement as well as controlled image enhancement, automatic image segmentation is applied to avoid the influence of disturbing factors (e.g. metallic restorations) on quality measurement and image enhancement. Based on existing a-priori knowledge about object structure and composition of the selected regions of interest in intraoral radiographs, different image segmentation algorithms and image enhancement procedures were developed for different types of diagnosis. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

  • 17. Kordaß, B.
    et al.
    Gärtner, Ch.
    Söhnel, A.
    Bisler, A.
    Voß, G.
    Bockholt, U.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    The virtual articulator in dentistry: concept and development2002Inngår i: Dental Clinics of North America, ISSN 1558-0512, Vol. 46, nr 3, s. 493-506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Virtual Reality (VR) technology is one of the most important innovations for research, development, and industrial production. In dentistry, VR technology will be useful in providing better education through simulation and in enhancing working procedures that are conventionally limited, e.g., the mechanical articulator. It is the purpose of this article to present concepts and strategies for a future replacement of the mechanical articulator by a virtual one.

  • 18.
    Lim, Nancy Joy
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Brandt, S. Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Division of Visual Information and Interaction, Department of Information Technology, Uppsala University, Uppsala, Sweden.
    Visualisation and evaluation of flood uncertainties based on ensemble modelling2016Inngår i: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 30, nr 2, s. 240-262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study evaluates how users incorporate visualisation of flood uncertainty information in decision-making. An experiment was conducted where participants were given the task to decide building locations, taking into account homeowners’ preferences as well as dilemmas imposed by flood risks at the site. Two general types of visualisations for presenting uncertainties from ensemble modelling were evaluated: (1) uncertainty maps, which used aggregated ensemble results; and (2) performance bars showing all individual simulation outputs from the ensemble. Both were supplemented with either two-dimensional (2D) or three-dimensional (3D) contextual information, to give an overview of the area.The results showed that the type of uncertainty visualisation was highly influential on users’ decisions, whereas the representation of the contextual information (2D or 3D) was not. Visualisation with performance bars was more intuitive and effective for the task performed than the uncertainty map. It clearly affected users’ decisions in avoiding certain-to-be-flooded areas. Patterns to which the distances were decided from the homeowners’ preferred positions and the uncertainties were similar, when the 2D and 3D map models were used side by side with the uncertainty map. On the other hand, contextual information affected the time to solve the task. With the 3D map, it took the participants longer time to decide the locations, compared with the other combinations using the 2D model.Designing the visualisation so as to provide more detailed information made respondents avoid dangerous decisions. This has also led to less variation in their overall responses.

  • 19.
    Lim, Nancy Joy
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Åhlén, Julia
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Geovisualisation of uncertainty in simulated flood maps2014Inngår i: Proceedings of the International Conferences on Interfaces and Human Computer Interaction 2014, Game and Entertainment Technologies 2014 and Computer Graphics, Visualization, Computer Vision and Image Processing 2014 - Part of the Multi Conference on Computer Science and Information Systems, MCCSIS 2014 / [ed] Katherine Blashki and Yingcai Xiao, IADIS Press , 2014, s. 206-214Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper presents a three-dimensional (3D) geovisualisation model of uncertainties in simulated flood maps that can help communicate uncertain information in the data being used. An entropy-based measure was employed for uncertainty quantification. In developing the model, Visualisation Toolkit (VTK) was utilised. Different data derived from earlier simulation study and other maps were represented in the model. Cartographic principles were considered in the map design. A Graphical User Interface (GUI), which was developed in Tkinter, was also created to further support exploratory data analysis. The resulting model allowed visual identification of uncertain areas, as well as displaying spatial relationship between the entropy and the slope values. This geovisualisation has still to be tested to assess its effectiveness as a communication tool. However, this type of uncertainty visualisation in flood mapping is an initial step that can lead to its adoption in decision-making when presented comprehensively to its users. Thus, further improvement and development is still suggested for this kind of information presentation.

  • 20. Lind, M.
    et al.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Mattiason, C.
    Displaying meta-information in context2001Inngår i: Behavior and Information Technology, ISSN 0144-929X, E-ISSN 1362-3001, Vol. 20, nr 6, s. 427-432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Very often information exists that would be helpful for process control operators if it could be presented in the context they work in-the process graphics. Examples are instructional material, visualizations of automated sequences, output from knowledge-based systems or simply annotations that one team of operators wants to communicate with another. Several existing distortion techniques were reviewed that would allow the ordinary process graphics to take less space leaving room for additional information. However, these techniques were rejected, mainly because all parts of a process control screen need to be readable at all times. A new technique is proposed and its readability experimentally evaluated with promising results.

  • 21.
    Liu, Fei
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Detection of Façade Regions in Street View Images from Split-and-Merge of Perspective Patches2014Inngår i: Journal of Image and Graphics, ISSN ISSN 2301-3699, Vol. 2, nr 1, s. 8-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Identification of building façades from digital images is one of the central problems in mobile augmented reality (MAR) applications in the built environment. Directly analyzing the whole image can increase the difficulty of façade identification due to the presence of image portions which are not façade. This paper presents an automatic approach to façade region detection given a single street view image as a pre-processing step to subsequent steps of façade identification. We devise a coarse façade region detection method based on the observation that façades are image regions with repetitive patterns containing a large amount of vertical and horizontal line segments. Firstly, scan lines are constructed from vanishing points and center points of image line segments. Hue profiles along these lines are then analyzed and used to decompose the image into rectilinear patches with similar repetitive patterns. Finally, patches are merged into larger coherent regions and the main building façade region is chosen based on the occurrence of horizontal and vertical line segments within each of the merged regions. A validation of our method showed that on average façade regions are detected in conformity with manually segmented images as ground truth.

  • 22.
    Liu, Fei
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Detection of Line Features in Digital Images of Building Structures2012Inngår i: Proceedings of IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing 2012 (CGVCVIP 2012) / [ed] Yingcai Xiao, 2012, s. 163-167Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes method for detection of short line segments in digital images. It aims at identifying buildingsin images taken from the ground view. The process starts with the image edge map and is carried out in twodifferent levels. One is to detect long line segments usually stemming from façade edges and building silhouettes.The other one identifies shorter line segments which typically represent architectural details such as windows andentrances. Selected individual connected components in both vertical and horizontal gradient component mapsare used respectively as input to the Hough transform at this level. Our first result shows that this method iscapable of recognizing lines of interest but has also included many randomly oriented lines. The next step will beto eliminate the random line segments and correlate line segments of the two levels to classify high-level features ofbuildings in an image.

  • 23.
    Liu, Fei
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
    Infrared-visible image registration for augmented reality-based thermographic building diagnostics2015Inngår i: Visualization in Engineering, ISSN 2213-7459, Vol. 3, nr 1, artikkel-id 16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: In virtue of their capability to measure temperature, thermal infrared cameras have been widely used in building diagnostics for detecting heat loss, air leakage, water damage etc. However, the lack of visual details in thermal infrared images makes the complement of visible images a necessity. Therefore, it is often useful to register images of these two modalities for further inspection of architectures. Augmented reality (AR) technology, which supplements the real world with virtual objects, offers an ideal tool for presenting the combined results of thermal infrared and visible images. This paper addresses the problem of registering thermal infrared and visible façade images, which is essential towards developing an AR-based building diagnostics application. Methods: A novel quadrilateral feature is devised for this task, which models the shapes of commonly present façade elements, such as windows. The features result from grouping edge line segments with the help of image perspective information, namely, vanishing points. Our method adopts a forward selection algorithm to determine feature correspondences needed for estimating the transformation model. During the formation of the feature correspondence set, the correctness of selected feature correspondences at each step is verified by the quality of the resulting registration, which is based on the ratio of areas between the transformed features and the reference features. Results and conclusions: Quantitative evaluation of our method shows that registration errors are lower than errors reported in similar studies and registration performance is usable for most tasks in thermographic inspection of building façades.

  • 24.
    Milutinovic, Goran
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Datavetenskap.
    Ahonen-Jonnarth, Ulla
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Besluts-, risk- och policyanalys.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Datavetenskap. Division of Visual Information and Interaction, Department of Information Technology, Uppsala University, Uppsala, Sweden.
    Brandt, S. Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Samhällsbyggnad.
    The impact of interactive visualization on trade-off-based geospatial decision-making2019Inngår i: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 33, nr 10, s. 2094-2123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a previous work we developed GISwaps, a novel method for geospatial decision-making based on Even Swaps. In this paper, we present the results of an evaluation of a visualization framework integrated with this method, implemented within a decision support system. This evaluation is based on two different studies. In the quantitative study, 15 student participants used GISwaps with no visual features, and 15 participants used GISwaps with the integrated visual framework, as the tool in a solar farm site location case study. The results of the quantitative evaluation show positive impact of the visualization in terms of increased coherency in trade-offs. The results also show a statistically significant difference in average trade-off values between the groups, with users from the non-visual group setting on average 20% higher trade-off values compared with the users in the visual group. In the qualitative study, we had one expert in GIS, two experts in decision-making and two experts in solar energy as a focus user group. Data in this study were obtained by observations and semi-structured interviews with the participants. The impact of the visualization framework was assessed positively by all participants in the expert group. 

  • 25. Nyström, Ingela
    et al.
    Olsson, Pontus
    Nysjö, Johan
    Nysjö, Fredrik
    Malmberg, Filip
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Hirsch, Jan-Michel
    Carlbom, Ingrid B.
    Virtual Cranio-Maxillofacial Surgery Planning with Stereo Graphics and Haptics2016Inngår i: Computer-Assisted Musculoskeletal Surgery: Thinking and Executing in 3D / [ed] Ritacco, L .E. and Milano, F. E. and Chao, E., Springer Publishing Company, 2016, 1, s. 29-42Kapittel i bok, del av antologi (Fagfellevurdert)
  • 26.
    Ohlsson, P
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Real-time Rendering of Accumulated Snow2004Inngår i: Proceedings of the Annual SIGRAD Conference, 2004, s. 25-32Konferansepaper (Annet vitenskapelig)
  • 27. Olsson, E
    et al.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Jansson, A
    Safer navigation at sea using augmented reality2002Inngår i: Proceedings of HCI'02, People and Computers, 2002, s. 154-157Konferansepaper (Annet vitenskapelig)
  • 28.
    Olsson, Pontus
    et al.
    Uppsala University, Uppsala, Sweden.
    Nysjö, Fredrik
    Uppsala University, Uppsala, Sweden.
    Aneer, Björn
    Independent Artist, Stockholm, Sweden .
    Seipel, Stefan
    Uppsala University, Uppsala, Sweden.
    Carlbom, Ingrid
    Uppsala University, Uppsala, Sweden.
    SplineGrip - An eight degrees-of-freedom flexible haptic sculpting tool2013Inngår i: Proceeding SIGGRAPH '13 ACM SIGGRAPH 2013 Posters, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Haptic sculpting allows a designer to create virtual models with the aid of haptic feedback. Just as in real life sculpting, different tools are used to work the model into a desired shape. Several haptic sculpting tools appear in the literature. For example, [Gao 2006] proposes an ellipsoidal tool whose pose (position and orientation) is controlled by a six degrees-of-freedom (DOF) haptic device, and [McDonnell 2001] describes a set of modeling tools for virtual clay controlled by three DOF haptics.

  • 29.
    Olsson, Pontus
    et al.
    Uppsala universitet, Informationsteknologi.
    Nysjö, Fredrik
    Uppsala universitet, Informationsteknologi.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Carlbom, Ingrid
    Uppsala universitet, Informationsteknologi.
    Physically Co-Located Haptic Interaction with 3D Displays2012Inngår i: Proc. Haptics Symposium (HAPTICS), 2012 IEEE, 2012, s. 267-272Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Studies indicate that haptic interaction with a computer generated virtual scene may become more intuitive by aligning (co-locating) the visual and haptic workspaces so that the visual and haptic feedback coincide as they do in the real world. Co-located haptics may gain importance when more advanced haptic interfaces, such as high-fidelity whole hand devices, become available. We describe a user study that investigates the pros and cons with physically co-located versus non-collocated haptics on two different display types: a commercial half-transparent mirror 3D display with shutter glasses and a prototype autostereoscopic display based on a Holographic Optical Element (HOE). We use two accuracy tasks with spatial accuracy as the dependent variable and one manipulation task with time as the dependent variable. The study shows that on both displays co-location significantly improves completion time in the manipulation task. However, the study shows that co-location does not improve the accuracy in the spatial accuracy tasks.

  • 30. Pettersson, L W
    et al.
    Jemsen, N
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    A Virtual Laboratory for Computer Graphics Education2003Inngår i: Proceedings of EUROGRAPHICS Conference 2003, Granada, Spain. 1-6 September 2003, 2003, s. 17-21Konferansepaper (Annet vitenskapelig)
  • 31. Pettersson, L W
    et al.
    Kjellin, A
    Lind, M
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Effects of layer partitioning in collaborative 3D visualizations2006Inngår i: Advances in Visual Computing: Second International Symposium, ISVC 2006 Lake Tahoe, NV, USA, November 6-8, 2006 Proceedings, Part I, Berlin, Heidelberg: Springer , 2006, s. 180-190Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Display technologies that support multiple independent views of the same co-located 3D visualization volume make new forms of collaboration possible. In this field of research, until now most efforts have focused on technical solutions and their applications. The main contribution of this paper is the results from a study comparing integral and partitioned 3D content in a head coupled stereoscopic environment through independent views of a shared 3D visualization.

    In our study we used a geospatial task that was solved by ten pairs of collaborating individuals (dyads). We measured task performance by time and error rate for the dyads in two main conditions: a) an integral visualization that presented a map in the display surface and four layers at different depths below the display surface to each of the observers, and b) a partitioned visualization, where two mutually exclusive subsets of the layers were presented to each of the observers together with the map in the display surface.

    The results from the study showed significant differences in regard to performance times between the two conditions. Task performance was significantly better in the condition with layer partitioning. Partitioned visualizations can thus, at least in some cases, improve performance in tasks requiring collaboration between users.

  • 32. Pettersson, L W
    et al.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Collaborative 3D Visualizations of Geo-Spatial Information for Command and Control2004Inngår i: Proceedings of the Annual SIGRAD Conference, 2004, s. 41-47Konferansepaper (Annet vitenskapelig)
  • 33. Pettersson, L W
    et al.
    Wesslén, Daniel
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    In situ tomographic display for interactive data visualization2004Inngår i: Proceedings of the third Nordic conference on Human-Computer Interaction, 2004Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    With tomographic in situ visualization we present a novel approach to interactive data visualization and exploration. This visualization concept is useful for presentation of spatially co-located information that is normally not visible to the human's eye. The tomographic in situ display allows for interactive cutting through data in space by using a spatially tracked and calibrated display. In this paper we describe the technical apparatus of our prototype and describe an application for the tomographic in situ visualization in the field of indoor climate studies.

  • 34. Pettersson, Lars Winkler
    et al.
    Lind, M
    Spak, Ulrik
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Visualization of symbols in a horizontal multiple viewer 3D display environment2005Inngår i: Proceedings of IEEE Information Visualization 2005, 2005, s. 357-362Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this paper we present a visualization environment for collaborative and co-located displays of geospatially related data for command and control. We first describe the working principle of a novel horizontal display that is aimed at providing high resolution stereoscopic 3D visualizations simultaneously to a group of up to four observers. This display environment opens up new ways to present view-dependent visual content within a shared workspace. For this environment we propose frontoparallel presentations of conventional symbols that are 3D presentations of 2D symbols which appear virtually oriented towards the line of sight of the observer. In an experiment we compare frontoparallel symbols with flat symbols i.e. symbols that are presented in the horizontal plane of the display. The results of our study indicate that frontoparallel symbols in a stereoscopic view are perceived and identified faster than symbols presented flat in relation to the plane of the display.

  • 35.
    Ren, Zheng
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Samhällsbyggnad.
    Jiang, Bin
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Samhällsbyggnad.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Datavetenskap.
    Capturing and characterizing human activities using building locations in America2019Inngår i: ISPRS International Journal of Geo-Information, ISSN 2220-9964, Vol. 8, nr 5, artikkel-id 200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Capturing and characterizing collective human activities in a geographic space have become much easier than ever before in the big era. In the past few decades it has been difficult to acquire the spatiotemporal information of human beings. Thanks to the boom in the use of mobile devices integrated with positioning systems and location-based social media data, we can easily acquire the spatial and temporal information of social media users. Previous studies have successfully used street nodes and geo-tagged social media such as Twitter to predict users’ activities. However, whether human activities can be well represented by social media data remains uncertain. On the other hand, buildings or architectures are permanent and reliable representations of human activities collectively through historical footprints. This study aims to use the big data of US building footprints to investigate the reliability of social media users for human activity prediction. We created spatial clusters from 125 million buildings and 1.48 million Twitter points in the US. We further examined and compared the spatial and statistical distribution of clusters at both country and city levels. The result of this study shows that both building and Twitter data spatial clusters show the scaling pattern measured by the scale of spatial clusters, respectively, characterized by the number points inside clusters and the area of clusters. More specifically, at the country level, the statistical distribution of the building spatial clusters fits power law distribution. Inside the four largest cities, the hotspots are power-law-distributed with the power law exponent around 2.0, meaning that they also follow the Zipf’s law. The correlations between the number of buildings and the number of tweets are very plausible, with the r square ranging from 0.53 to 0.74. The high correlation and the similarity of two datasets in terms of spatial and statistical distribution suggest that, although social media users are only a proportion of the entire population, the spatial clusters from geographical big data is a good and accurate representation of overall human activities. This study also indicates that using an improved method for spatial clustering is more suitable for big data analysis than the conventional clustering methods based on Euclidean geometry.

  • 36.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Centre of Image Analysis, Uppsala University, Uppsala, Sweden.
    Evaluating 2D and 3D Geovisualizations for Basic Spatial Assessment2013Inngår i: Behavior and Information Technology, ISSN 0144-929X, E-ISSN 1362-3001, Vol. 32, nr 8, s. 845-858Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigates the use of 2D and 3D presentations of maps for the assessment of distances in a geographicalcontext. Different types of 3D representations have been studied: A weak 3D visualisation that provides staticmonocular depth cues and a strong 3D visualisation that uses stereoscopic and kinetic depth cues. Two controlledexperiments were conducted to test hypotheses regarding subjects’ efficiency in visually identifying the shortestdistance among a set of market locations in a map. As a general result, we found that participants were able tocorrectly identify shortest distances when the difference to potential alternatives was sufficiently large, butperformance decreased systematically when this difference decreased. Noticeable differences emerged for theinvestigated visualisation conditions. Participants in this study were equally efficient when using a weak 3Drepresentation and a 2D representation. When the strong 3D visualisation was employed, they reported visualdiscomfort and tasks were solved significantly less correct. Presentations of intrinsic 2D content (maps) in 3Dcontext did, in this study, not benefit from cues provided by a strong 3D visualisation and are adequatelyimplemented using a weak 3D visualisation.

  • 37.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Information Visualization using Transparent Shape Impostors2003Inngår i: Proceedings of EUROGRAPHICS Conference 2003, 2003, s. 249-254Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Transparency is a graphical effect used in visualizations to present co-located graphical glyphs. Accomplishinga visually convincing transparency effect requires complex calculations of light absorption andrefraction in object space. Alternatively, screen-space sorted rendering of graphical primitives using colour-blending techniques can be used for interactive applications. In this paper an efficient way is presentedto render transparent glyphs for information visualization. The technique combines random dotsurface plots with pre-computed transparent shape impostors to present different levels of transparencyfor co-located graphical glyphs. It is shown that this rendering method is faster than ordered polygonrendering using blending.

  • 38.
    Seipel, Stefan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Uppsala universitet.
    Solving Geospatial Tasks in 2D and 3D Visualisation of Maps2014Inngår i: Information Visualisation: Techniques, Usability and Evaluation / [ed] Ebad Banissi, Francis T. Marchese, Camilla Forsell and Jimmy Johansson, Newcastle upon Tyne: Cambridge Scholars Publishing, 2014, 1, s. 222-271Kapittel i bok, del av antologi (Fagfellevurdert)
  • 39.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Telematic dental articulation system for remote teaching in collaborative virtual Telemedicine2001Inngår i: Abstracts of the 6th International Conference on the Medical Aspects of Telemedicine, 2001Konferansepaper (Annet vitenskapelig)
  • 40.
    Seipel, Stefan
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Volumetric Normal Mapping in Rendering of Multivariate Volume Data2007Inngår i: Proceedings of Eurographics 2007 - Shortpapers and Medical Prices, Prague, September 3-7, 2007, s. 49-52Konferansepaper (Fagfellevurdert)
  • 41.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Ahreberg, L
    Distributed Rendering in Heterogeneous Display Environments: A Functional Framework Design and Performan Assessment2002Inngår i: Proceedings of the Annual SIGRAD Conference, 2002, s. 23-28Konferansepaper (Annet vitenskapelig)
  • 42.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap. Centre of Image Analysis, Uppsala University.
    Carvalho, Leonor
    University of Turku.
    Solving Combined Geospatial Tasks Using 2D and 3D Bar Charts2012Inngår i: 2012 16th International Conference on Information Visualisation, 2012, s. 157-163Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a user study that investigates2D and 3D visualizations of bar charts in geographic maps.The task to be solved by the participants in this studyrequired estimation of the ratio of two different spatial distancemeasures and relative ranking among potential candidates. Theresults of this experiment show that subjects were equally fastand accurate when using both the 2D and 3D visualizations.Visual discomfort was reported by almost half of the testpopulation, but performance was not affected. Our study alsoshowed that frequent game players did not benefit more froma 3D visualization than inexperienced game-players.

  • 43.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    A collaborative visualization environment for natural interaction with architectural content2009Inngår i: Proceedings of the 3rd ISPRS International Workshop 3D-ARCH 2009: "3D Virtual Reconstruction and Visualization of Complex Architectures" / [ed] Fabio Remondino, Sabry El-Hakim, Lorenzo Gonzo, 2009, s. XXXVIII-5/W1-Konferansepaper (Fagfellevurdert)
  • 44.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Designing Efficient Visualizations for Applications in the Paper and Pulp Industry2009Inngår i: Proceedings of IADIS Applied Computing 2009, Rome, November 19-21 / [ed] Hans Weghorn and Pedro Isaías, 2009Konferansepaper (Fagfellevurdert)
  • 45.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    On the Applicability of Direct and Indirect Input in Table-Top and Vertical Displays2009Inngår i: Proceedings of IADIS Applied Computing 2009, Rome, November 19-21 / [ed] Hans Weghorn and Pedro Isaías, 2009Konferansepaper (Fagfellevurdert)
  • 46.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Wesslén, Daniel
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Enhanced Visualizations of Thermographic Data in Process Industry2006Inngår i: EuroVis 06 / [ed] Beatriz Sousa Santos and Thomas Ertl and Kenneth I. Joy, Eurographics Association , 2006, s. 307-314Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this paper, we describe an improved method for visualization of thermographic data in the paper and pulp proc-ess industry. We present an application that allows process operators to freely choose how absolute temperatures and time varying changes of thermographic scans should be mapped to colors and/or 3D shapes. Of the possible combinations, we selected two different forms of 3D visualizations and an existing conventional 2D map visualiza-tion. We then evaluated these visualization forms with regard to their effectiveness in experimental field studies. The field tests were carried out to measure the operators’ performance in early detection of insulation damages on lime kilns. The results we obtained from the study show that the two new forms of 3D visualization lead to a reduc-tion of the detection times by about two-thirds and one-third, respectively, when compared to the conventional 2D map representation. Since lime kiln monitoring is based on the rather generic method of continuous thermographic imaging, we suggest that these results also hold for the control and surveillance of other processes.

  • 47.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Hast, Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    A Local Curvature Based Lighting Model for Rendering of Snow2010Inngår i: Proceedings of IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing 2010 (CGVCVIP 2010) / [ed] Yingcai Xiao, Tomaz Amon and Roberto Muffoletto, 2010, s. 367-372Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Local illumination models try to describe the interaction between light and objects in the scene based on only few parameters representing some geometric and material properties at a given point on a surface. In this paper we present our research in local illumination models for the purpose of approximating light transport and shadow-masking effects in the local neighborhood of the surface point under evaluation. We assume that the amount of curvature at a surface point to some extent represents geometric properties in the surrounding neighborhood of this point. From this we define an empirical illumination model for diffuse reflecting materials which controls the amount of locally scattered light from the neighborhood as well as subsurface light transport based on some curvature metric.

  • 48.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Jenke, Peter
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Quantification of gaseous structures with volumetric reconstruction from visual hulls2011Inngår i: Proceedings of SIGRAD 2011. Evaluations of Graphics and Visualization, November 17–18, 2011, KTH, Stockholm, Sweden, 2011, s. 77-82Konferansepaper (Fagfellevurdert)
    Abstract [en]

    3D reconstruction from visual hulls is a well established technique for camera based reconstruction of 3D objects in computer graphics. We propose in this paper to employ visual hull techniques to quantify the volume of diffusely defined gaseous structures. In our evaluation, visual quality of the 3D reconstructions is secondary. Instead, using synthetic ground truth data, we determine the number of independent silhouette images needed to achieve a stable volume estimate. We also estimate the influence of different segmentation results of the silhouette images on final volume estimates. Our results show that comparably few camera views yield to convergent volume estimates. For the type of 3D data studied, visual hull reconstructions overestimate actual volumes with about 50%. This proportion seems to be consistent for different data sets tested and may serve for re-calibration of volume estimation of gaseous structures.

  • 49.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Datavetenskap.
    Lim, Nancy J.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Color map design for visualization in flood risk assessment2017Inngår i: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 31, nr 11, s. 2286-2309Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Visualizations of flood maps from simulation models are widely used for assessing the likelihood of flood hazards in spatial planning. The choice of a suitable type of visualization as well as efficient color maps is critical to avoid errors or bias when interpreting the data. Based on a review of previous flood uncertainty visualization techniques, this paper identifies areas of improvements and suggests criteria for the design of a task-specific color scale in flood map visualization. We contribute a novel color map design for visualizing probabilities and uncertainties from flood simulation ensembles. A user study encompassing 83 participants was carried out to evaluate the effects of this new color map on user’s decisions in a spatial planning task. We found that the type of visualization makes a difference when it comes to identification of non-hazardous sites in the flood risk map and when accepting risks in more uncertain areas. In comparison with two other existing visualization techniques, we observed that the new design was superior both in terms of task compliance and efficiency. In regions with uncertain flood statuses, users were biased toward accepting less risky locations with our new color map design.

  • 50.
    Seipel, Stefan
    et al.
    Högskolan i Gävle, Institutionen för matematik, natur- och datavetenskap, Ämnesavdelningen för datavetenskap.
    Lindkvist, M
    Simulation based collaborative experiments for interactive learning in virtual classroom environments2001Inngår i: Proceedings of the 2nd European Conference on e-learning WBLE, 2001, s. 347-355Konferansepaper (Annet vitenskapelig)
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