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  • 1.
    Amor, Margarita
    et al.
    University of Coruna.
    Boo, Monsterrat
    University of Santiago de Compostela.
    Straβer, Wolfgang
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    A meshing scheme for efficient hardware implementation of butterfly subdivision using displacement mapping2005In: IEEE Computer Graphics and Applications, ISSN 0272-1716, E-ISSN 1558-1756, Vol. 25, no 2, p. 46-59Article in journal (Refereed)
    Abstract [en]

    Displacement mapping is an effective technique for encoding the high levels of detail of surface models using coarse triangle meshes and displacement maps. These maps are 2D representations containing the distances between the coarse mesh and the surface to represent. Displacement maps have been used in many applications such as ray tracing, image warping, and volume rendering. In this article, we propose modifications to our previous grouping strategy, a new subdivision strategy based on the Modified Butterfly algorithm and new heuristics for the adaptive subdivision procedure, and, finally, the corresponding modifications on our hardware proposal. A meshing scheme and an adaptive subdivision strategy based on displacement mapping reduce the bottleneck between the CPU and graphics pipeline common in high-performance graphics systems.

  • 2.
    Amor, Margarita
    et al.
    University of Coruna.
    Boo, Montserrat
    University of Santiago de Compostela.
    Doggett, Michael
    ATI Research.
    Hirche, Johannes
    Straßer, Wolfgang
    WSI/GRIS, University of Tübingen.
    A meshing scheme for memory efficient adaptive rendering of subdivision surfaces2000Report (Other academic)
  • 3.
    Bomark, Peter
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Evertsen, Gunn
    Northern Research Institute.
    Brox, Ellen
    Northern Research Institute.
    Hirche, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yliräisänen-Seppänen, Pia
    Rovaniemi University of Applied Sciences.
    A prototype social learning platform for children with diabetes type 12012In: Proceeding of the 16th International Academic MindTrek Conference 2012: Envision Future Media Environments, New York: Association for Computing Machinery, Inc. , 2012, p. 211-213Conference paper (Refereed)
    Abstract [en]

    Children diagnosed with diabetes type 1 are bombarded with information and have a hard time understanding it all. Existing information material consists mostly ofbrochures and textbooks, giving little opportunity for testing and trial-and-error without consequences. A social platform with learning games gives the children an opportunity to experiment and find peer support, which is important for coping with a life long disease.

  • 4.
    Bomark, Peter
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hirche, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Colour visualisation of real virtual timber using image quilting2015In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, no 6, p. 837-839Article in journal (Refereed)
    Abstract [en]

    When presenting images of wood obtained through x-ray computed tomography to an audience inexperienced in interpreting radiological images, explaining the correspondence between mass attenuation and features of wood could be time consuming and confusing. Realistically colourised attenuation images might be a suitable option in order to facilitate understanding of the images. Mass attenuation and colour of wood does not have a simple correlation, so naive grey-scale to colour conversion does not work. This paper describes how image quilting can be used to transfer colour information from a image pair where both mass attenuation and colour is known to a target mass attenuation image. An example of this method applied on scots pine shows that it is capable of retaining the major structures of wood, such as year rings and knots. The method could allow for easier understanding of simulation studies where logs scanned using x-ray computed tomography are virtually sawn.

  • 5.
    Brox, Ellen
    et al.
    Northern Research Institute.
    Evertsen, Gunn
    Northern Research Institute.
    Bomark, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hirche, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yliräisänen-Seppänen, Pia
    Rovaniemi University of Applied Sciences.
    User centric social diabetes game design for children2012In: Proceeding of the 16th International Academic MindTrek Conference 2012: Envision Future Media Environments, New York: Association for Computing Machinery, Inc. , 2012, p. 291-293Conference paper (Refereed)
    Abstract [en]

    Children recently diagnosed with diabetes type 1 require lots ofinformation and feel scared, alone and different. Most of theexisting educational material is on paper. Games with relevantlearning content are mainly small minigames in English. There isa need for more material with a focus on user needs, particularlylearning–by-doing material. Peer support is known to beimportant for this user group. We present a concept for a sociallearning game that is engaging and fun for diabetic children.

  • 6.
    Cepeda, Montserrat Bóo
    et al.
    University of Santiago de Compostela.
    Amor, Margarita
    Department of Electronic and Systems, University of La Coruña.
    Doggett, Michael
    AMD.
    Hirche, Johannes
    Strasser, Wolfgang
    WSI/GRIS, University of Tübingen.
    Hardware support for adaptive subdivision surface rendering2001In: Proceedings of the ACM SIGGRAPH/EUROGRAPHICS Workshop on Graphics Hardware: Los Angeles, California, United States, 2001 / [ed] Hanspeter Pfister, New York: Association for Computing Machinery (ACM), 2001, p. 33-40Conference paper (Refereed)
    Abstract [en]

    Adaptive subdivision of triangular meshes is highly desirable for surface generation algorithms including adaptive displacement mapping in which a highly detailed model can be constructed from a coarse triangle mesh and a displacement map. The communication requirements between the CPU and the graphics pipeline can be reduced if more detailed and complex surfaces are generated, as in displacement mapping, by an adaptive tessellation unit which is part of the graphics pipeline. Generating subdivision surfaces requires a large amount of memory in whicmultiple arbitrary accesses are required to neighbouring vertices to calculate the new vertices. In this paper we present a meshing scheme and new architecture for the implementation of adaptive subdivision of triangular meshes that allows for quick access using a small memory making it feasible in hardware, while at the same time allowing for new vertices to be adaptively inserted. The architecutre is regular and characterized by an efficient data management that minimizes the data storage and avoids the wait cycles that would be associated with the multiple data accesses required for traditional subdivision. This architecture is presented as an improvement for adaptive displacement mapping algorithms, but could also be used for adaptive subdivision surface generation in hardware.

  • 7.
    Doggett, Michael
    et al.
    AMD.
    Hirche, Johannes
    Adaptive view dependent tessellation of displacement maps2000In: Proceedings, 2000 SIGGRAPH/EUROGRAPHICS Workshop on Graphics Hardware, Interlaken, Switzerland, August 21-22, 2000, New York: Association for Computing Machinery (ACM), 2000, p. 59-66Conference paper (Refereed)
    Abstract [en]

    Displacement Mapping is an effective technique for encoding the high levels of detail found in today's triangle based surface models. Extending the hardware rendering pipeline to be capable of handling displacement maps as geometric primitives, will allow highly detailed models to be constructed without requiring large numbers of triangles to be passed from the CPU to the graphics pipeline. We present a new approach based on recursive tessellation that adapts to the surface complexity described by the displacement map. We also ensure that the resolution of the displaced mesh is tessellated with respect to the current view point. Our tessellation scheme performs all tests only on triangle edges to avoid generating cracks on the displaced surface. The main decision for vertex insertion is based on two comparisons involving the average height surrounding the vertices and the normals at the vertices. Individually, the tests will fail to tessellate a mesh satisfactorily, but their combination achieves good results. We propose several additions to the typical hardware rendering pipeline in order to achieve displacement map rendering in hardware. The mesh tessellation is placed within the rendering pipeline so that we can take advantage of the pre-existing vertex transformation units to perform the setup calculations for our view dependent test. Our method adds only simple arithmetic and comparison operations to the graphics pipeline and makes use of existing units for calculations wherever possible

  • 8.
    Doggett, Michael
    et al.
    AMD.
    Hirche, Johannes
    Displacement mapping rendering hardware using adaptive tessellation2000Conference paper (Refereed)
  • 9.
    Hirche, Johannes
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Bomark, Peter
    Natural User Interface Europe AB.
    Bauer, Mikael
    Natural User Interface Europe AB.
    Solyga, Pawel
    Natural User Interface Europe AB.
    Adaptive interface for text input on large-scale interactive surfaces2008In: 2008 IEEE International Workshop on Horizontal Interactive Human-Computer System: Amsterdam, Netherlands, 1 - 3 October 2008, Piscataway, NJ: IEEE Communications Society, 2008, p. 163-166Conference paper (Refereed)
    Abstract [en]

    In this paper we present a novel approach to text input on large interactive surfaces using a combination of strategies to resolve the inherent difficulties with text input on such a device. Instead of using a conventional full size QWERTY based layout, the idea is to use a very limited set of buttons that, by using word prediction and hints, would only require minimal finger movement. The input mechanism is somewhat related to input methods employed when using keyboards with a limited size and amount of keys, commonly found in phones and other 10 digit keyboards. Given that the main motivation to this approach was not the limited size but rather to overcome the difficult task of locating keys with fingers on a flat and featureless surface, making touchtyping very difficult and requiring frequent visual monitoring of the finger position, we opted to enhance the interaction with easily made gestures, a layout that adapts to the hand anatomy of the user, and easy control over the text prediction.

  • 10. Hirche, Johannes
    et al.
    Ehlert, Alexander
    WSI/GRIS, University of Tübingen.
    Curvature maps2003Report (Other academic)
  • 11. Hirche, Johannes
    et al.
    Ehlert, Alexander
    WSI/GRIS, University of Tübingen.
    Curvature-driven sampling of displacement maps2002Conference paper (Refereed)
  • 12. Hirche, Johannes
    et al.
    Ehlert, Alexander
    University of Tübingen.
    Guthe, Stefan
    University of Tübingen.
    Doggett, Michael
    ATI Research.
    Hardware accelerated per-pixel displacement mapping2004In: Graphics Interface 2004: proceedings ; London, Ontario, 17 - 19 May 2004 / [ed] Wolfgang Heidrich, A K Peters , 2004, p. 153-158Conference paper (Refereed)
    Abstract [en]

    In this paper we present an algorithm capable of rendering a displacement mapped triangle mesh interactively on latest GPUs. The algorithm uses only pixel shaders and does not rely on adaptively adding geometry. All sampling of the displacement map takes place in the pixel shader and bi- or trilinear ltering can be applied to it, and at the same time as the calculations are done per pixel in the shader, the algorithm has automatic level of detail control. The triangles of the base mesh are extruded along the respective normal directions and then the resulting prisms are rendered by casting rays inside and intersecting them with the displaced surface. Two different implementations are discussed in detail.

  • 13.
    Kanus, Urs
    et al.
    WSI/GRIS, University of Tübingen.
    Wetekam, Gregor
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    VoxelCache: a cache-based memory architecture for volume graphics2003In: Proceedings of the ACM SIGGRAPH/EUROGRAPHICS conference on Graphics Hardware: San Diego, California, July 26-27, 2003, New York: Association for Computing Machinery (ACM), 2003, p. 76-83Conference paper (Refereed)
    Abstract [en]

    This paper presents a cache-based memory architecture for volume graphics. We describe the memory organization and cache logic to implement a voxel cache based on 43 voxel blocks. We show an efficient prefetching scheme that increases the cache hit ratio to more than 98% in most cases. The performance of the memory system with different types of external memory is demonstrated by a cycle accurate C++ simulation. The VoxelCache memory architecture is designed to be easily adapted to different memory technologies, because all volume graphics specific parts of the memory system are encapsulated inside the on-chip cache. The design is targeted at implementation on off-the-shelf reconfigurable hardware.

  • 14.
    Kanus, Urs
    et al.
    WSI/GRIS, University of Tübingen.
    Wetekam, Gregor
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    Meißner, Michael
    WSI/GRIS, University of Tübingen.
    VIZARDII: An FPGA-based Interactive Volume Rendering System2002Conference paper (Other academic)
    Abstract [en]

    In this paper we present a volume rendering system that implements a Direct Volume Rendering algorithm on a Xilinx FPGA being capable of visualizing 3D-datasets with highest image quality at interactive frame rate. The volume renderer utilizes a cache optimized memory scheme for maximum memory bandwidth and a fully pipelined architecture of the computational expensive rendering calculations. The used ray-casting algorithm was adapted in critical parts to fit the specific need of an efficient hardware usage, with respect to available resources and computational power, without limiting rendering features. Using a FPGA approach offers full flexibility to the implementation of the algorithm making it easy to adapt and extend new features to the rendering pipeline without the need of time consuming redesigns, especially important in a scientific environment.

  • 15.
    Konstantinidis, Stathis
    et al.
    NORUT Northern research institute.
    Brox, Ellen
    NORUT Northern research institute.
    Kommervold, Per Egil
    NORUT Northern research institute.
    Hallberg, Josef
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Evertsen, Gunn
    NORUT Northern research institute.
    Hirche, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Online Social Exergames for Seniors: Pillar of Gamification for Clinical Practice2016In: Handbook of Research on Holistic Perspectives in Gamification for Clinical Practice, IGI Global, 2016, p. 245-276Chapter in book (Refereed)
    Abstract [en]

    The population is getting older, and the resources for care will be even more limited in the future than they are now. There is thus an aim for the society that the seniors can manage themselves as long as possible, while at the same time keeping a high quality of life. Physical activity is important to stay fit, and social contact is important for the quality of life. This chapter aims to provide a state-of-the-art of online social exergames for seniors, providing glimpses of senior users’ opinions and games limitations. The importance of the motivational techniques will be emphasized, as well as the impact that the exergames have to seniors. It will contribute to the book objectives focusing on current state and practice in health games for physical training and rehabilitation and the use of gamification, exploring future opportunities and uses of gamification in eHealth and discussing the respective challenges and limitations.

  • 16.
    Kugler, Anders
    et al.
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    Texturing ASIC specification2008Report (Other academic)
  • 17.
    Kugler, Anders
    et al.
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    Trirast: A rendering processor architecture for advanced texture shading1998Report (Other academic)
  • 18.
    Meißner, Michael
    et al.
    WSI/GRIS, University of Tübingen.
    Doggett, Michael
    AMD.
    Kanus, Urs
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    Accelerating volume rendering using an on-chip sram occupancy map2001In: ISCAS 2001 :: the 2001 IEEE International Symposium on Circuits and Systems : conference proceedings : 6-9 May 2001, Sydney Convention and Exhibition Centre, Darling Harbour, Sydney, Australia, Piscataway, NJ: IEEE Communications Society, 2001, Vol. 2, p. 757-760Conference paper (Refereed)
    Abstract [en]

    One of the most severe problems for ray casting architectures is the waste of computation cycles and I/O bandwidth, due to redundant sampling of empty space. While several techniques exist for software implementations to skip these empty regions, few are suitable for hardware implementation. The few which have been presented either require a tremendous amount of logic or are not feasible for high frequency designs (i.e. running at 100 MHz) where latency is the one of the biggest issues. In this paper, we present an efficient space leaping approach which requires only a small amount of SRAM (4 Kbit for a 256 3 volume) and can be easily integrated into ray casting architectures. For each subcube of the volume, a bit is stored in an occupancy map, indicating whether the subcube is empty or not. Using a set of real-world datasets, we show that frame-rates well above 15 frames per second can be accomplished for the VIZARD II volume rendering architecture

  • 19.
    Meißner, Michael
    et al.
    WSI/GRIS, University of Tübingen.
    Doggett, Michael
    AMD.
    Kanus, Urs
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    Straßer, Wolfgang
    WSI/GRIS, University of Tübingen.
    Efficient Space Leaping for Raycasting Architectures2008In: Volume graphics 2001 in Stony Brook: proceedings of the Joint IEEE TCVG and Eurographics Workshop in Stony Brook, New York, USA, June 21 - 22, 2001, Eurographics / [ed] Klaus Mueller, Wien: Encyclopedia of Global Archaeology/Springer Verlag, 2008Conference paper (Refereed)
  • 20.
    Meißner, Michael
    et al.
    WSI/GRIS, University of Tübingen.
    Kanus, Urs
    WSI/GRIS, University of Tübingen.
    Wetekam, Gregor
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    Ehlert, Alexander
    WSI/GRIS, University of Tübingen.
    Straßer, Wolfgang
    WSI/GRIS, University of Tübingen.
    Doggett, Michael
    AMD.
    Forthmann, P
    Philips Research Hamburg.
    Proksa, R
    Philips Research Hamburg.
    VIZARD II: a reconfigurable interactive volume rendering system2002In: Proceedings of the ACM SIGGRAPH/EUROGRAPHICS conference on Graphics Hardware: Saarbrücken, Germany, September 01-02, 2002 / [ed] Anselmo Lastra; Thomas Ertl, New York: Association for Computing Machinery (ACM), 2002, p. 137-146Conference paper (Refereed)
    Abstract [en]

    This paper presents a reconfigurable, hardware accelerated, volume rendering system for high quality perspective ray casting. The volume rendering accelerator performs ray casting by calculating the path of the ray through the volume using a programmable Xilinx Virtex FPGA which provides fast design changes and low cost development. Volume datasets are stored on the card in low profile DIMMs with standard connectors allowing both, large datasets up to 1 GByte with 32 bit per voxel, and easy upgrades to larger memory capacities. Per-sample Phong shading and post-classification is performed in hardware, giving immediate feedback to changes in the visualization of a dataset. Adding new features, such as pre-integrated classification, can be accomplished using the existing card without expensive and time consuming redesigns. The card can also be used for medical image reconstruction by reconfiguring the FPGA broadening its usefulness for end users. For the first time, users are able to generate high quality perspective images as required for applications such as virtual endoscopy and colonoscopy, and stereoscopic image generation.

  • 21.
    Meißner, Michael
    et al.
    WSI/GRIS, University of Tübingen.
    Wetekam, Gregor
    WSI/GRIS, University of Tübingen.
    Hirche, Johannes
    Kanus, Urs
    WSI/GRIS, University of Tübingen.
    Accomodating pipeline latency for high clock frequency image order volume rendering architectures2001Report (Other academic)
1 - 21 of 21
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