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  • 1. B Zafar, N
    et al.
    Åkesson, Johan
    Roble, D
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Scattered Spherical Harmonic Approximation for Accelerated Volume Rendering2006In: ACM SIGGRAPH ¿06 Sketches Applications,2006, 2006Conference paper (Refereed)
  • 2.
    Braude, I.
    et al.
    Department of Computer Science, Drexel University, Philadelphia, PA, United States.
    Marker, J.
    Department of Computer Science, Drexel University, Philadelphia, PA, United States.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Nissanov, J.
    Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.
    Breen, D.
    Department of Computer Science, Drexel University, Philadelphia, PA, United States.
    Contour-based surface reconstruction using MPU implicit models2007In: Graphical Models, ISSN 1524-0703, E-ISSN 1524-0711, Vol. 69, no 2, p. 139-157Article in journal (Refereed)
    Abstract [en]

    This paper presents a technique for creating a smooth, closed surface from a set of 2D contours, which have been extracted from a 3D scan. The technique interprets the pixels that make up the contours as points in R3 and employs multi-level partition of unity (MPU) implicit models to create a surface that approximately fits to the 3D points. Since MPU implicit models additionally require surface normal information at each point, an algorithm that estimates normals from the contour data is also described. Contour data frequently contains noise from the scanning and delineation process. MPU implicit models provide a superior approach to the problem of contour-based surface reconstruction, especially in the presence of noise, because they are based on adaptive implicit functions that locally approximate the points within a controllable error bound. We demonstrate the effectiveness of our technique with a number of example datasets, providing images and error statistics generated from our results. © 2006 Elsevier Inc. All rights reserved.

  • 3. Breen, David
    et al.
    Fedkiw, Ron
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Osher, Stanley
    Sapiro, G
    Whitaker, Ross
    Level Sets and PDE Methods for Computer Graphics2004Other (Other (popular science, discussion, etc.))
  • 4. Breen, David
    et al.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Level Sets Methods for Visualization2006Other (Other (popular science, discussion, etc.))
  • 5. Breen, David
    et al.
    Whitaker, Ross
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Zhukov, L
    Level Set Segmentation of Biological Volume Datasets2005In: Handbook of Medical Image Analysis: Volume 3, Registration models [Elektronisk resurs] / [ed] Jasjit S. Suri, David L. Wilson and Swamy Laxminarayan, New York: Kluwer , 2005, p. 415-478Chapter in book (Other academic)
    Abstract [en]

    Handbook of Biomedical Image Analysis: Registration Models (Volume III) is dedicated to the algorithms for registration of medical images and volumes. This volume is aimed at researchers and educators in imaging sciences, radiological imaging, clinical and diagnostic imaging, biomedical engineering, physicists covering different medical imaging modalities and researchers in applied mathematics, algorithmic development, computer vision, signal processing, computer graphics and multimedia in general, both in academia and industry.

  • 6.
    Brodersen, Anders
    et al.
    University of Aarhus.
    Museth, Ken
    Digital Domain.
    Porumbescu, Serban
    University of California.
    Budge, Brian
    University of California.
    Geometric Texturing Using Level Sets2008In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 14, no 2, p. 277-288Article in journal (Refereed)
    Abstract [en]

    We present techniques for warping and blending (or subtracting) geometric textures onto surfaces represented by high resolution level sets. The geometric texture itself can be represented either explicitly as a polygonal mesh or implicitly as a level set. Unlike previous approaches, we can produce topologically connected surfaces with smooth blending and low distortion. Specifically, we offer two different solutions to the problem of adding fine-scale geometric detail to surfaces. Both solutions assume a level set representation of the base surface which is easily achieved by means of a mesh-to-level-set scan conversion. To facilitate our mapping, we parameterize the embedding space of the base level set surface using fast particle advection. We can then warp explicit texture meshes onto this surface at nearly interactive speeds or blend level set representations of the texture to produce high-quality surfaces with smooth transitions.

  • 7.
    Brun, Anders
    et al.
    Centre for Image Analysis, Swedish University of Agricultural Sciences, Sweden.
    Nilsson, Ola
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Reimers, Martin
    Department of Informatics and Centre of Mathematics for Applications, University of Oslo, Norway.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Computing Riemannian Normal Coordinates on Triangle MeshesManuscript (preprint) (Other academic)
    Abstract [en]

    Imagine an ant walking around on the curved surface of a plant, a radio amateur planning to broadcast to a distant location across the globe or a pilot taking o from an airport - all of them are helped by egocentric maps of the world around them that shows directions and distances to various remote places. It is not surprising that this idea has already been used in cartography, where it is known as Azimuthal Equidistant Projection (AEP). If Earth is approximated by a sphere, distances and directions between two places are computed from arcs along great circles. In physics and mathematics, the same idea is known as Riemannian Normal Coordinates (RNC). It has been given a precise and general denition for surfaces (2-D), curved spaces (3-D) and generalized to smooth manifolds (N-D). RNC are the Cartesian coordinates of vectors that index points on the surface (or manifold) through the so called exponential map, which is a well known concept in dierential geometry. They are easily computed for a particular point if the inverse of the exponential map, the logarithm map, is known. Recently, RNC and similar coordinate systems have been used in computer graphics, visualization and related areas of research. In Fig. 1 for instance, RNC are used to produce a texture on the Stanford bunny through decal compositing. Given the growing use of RNC, which is further elaborated on in the next section, it is meaningful to develop accurate and reproducible techniques to compute this parameterization. In this paper, we describe a technique to compute RNC for surfaces represented by triangular meshes, which is the predominant representation of surfaces in computer graphics. The method that we propose has similarities to the Logmap framework, which has previously been developed for dimension reduction of unorganized point clouds in high-dimensional spaces, a.k.a. manifold learning. For this reason we sometimes refer to it as "Logmap for triangular meshes" or simply Logmap.

  • 8. Gómez, G
    et al.
    Lo, M
    Masdemont, J
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Simulation of Formation Flight Near Lagrange Points for the TPF Mission2001In: American Astronautical Society AAS/AIAA, Astrodynamics Specialist Conference,2001, 2001, p. 305-Conference paper (Refereed)
  • 9. Houston, B
    et al.
    Bang Nielsen, Michael
    Batty, C
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Gigantic Deformable Surfaces2005In: ACM SIGGRAPH 05, Sketches Applications,2005, 2005Conference paper (Refereed)
  • 10.
    Houston, Ben
    et al.
    Exocortex Technologies, Frantic Films.
    Nielson, Michael B.
    University of Århus.
    Batty, Christopher
    University of British Columbia, Frantic Films.
    Nilsson, Ola
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Hierarchical RLE level set: A compact and versatile deformable surface representation2006In: ACM Transactions on Graphics, ISSN 0730-0301, E-ISSN 1557-7368, Vol. 25, no 1, p. 151-175Article in journal (Refereed)
    Abstract [en]

    This article introduces the Hierarchical Run-Length Encoded (H-RLE) Level Set data structure. This novel data structure combines the best features of the DT-Grid ( of Nielsen and Museth [ 2004]) and the RLE Sparse Level Set ( of Houston et al. [ 2004]) to provide both optimal efficiency and extreme versatility. In brief, the H- RLE level set employs an RLE in a dimensionally recursive fashion. The RLE scheme allows the compact storage of sequential nonnarrowband regions while the dimensionally recursive encoding along each axis efficiently compacts nonnarrowband planes and volumes. Consequently, this new structure can store and process level sets with effective voxel resolutions exceeding 5000 x 3000 x 3000 ( 45 billion voxels) on commodity PCs with only 1 GB of memory. This article, besides introducing the H- RLE level set data structure and its efficient core algorithms, also describes numerous applications that have benefited from our use of this structure: our unified implicit object representation, efficient and robust mesh to level set conversion, rapid ray tracing, level set metamorphosis, collision detection, and fully sparse fluid simulation ( including RLE vector and matrix representations.) Our comparisons of the popular octree level set and Peng level set structures to the H- RLE level set indicate that the latter is superior in both narrowband sequential access speed and overall memory usage.

  • 11.
    Johansson, Gunnar
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Digital Media.
    Nilsson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Söderström, Andreas
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Distributed Ray Tracing in an Open Source Environment (Work in Progress)2006Conference paper (Refereed)
    Abstract [en]

    We present work in progress on concurrent ray tracing with distributed computers using ``off-the-shelf'' open source software. While there exists numerous open source ray tracers, very few offer support for state-of-the-art concurrent computing. However, it is a well known fact that ray tracing is computationally intensive and yet prevails as the preferred algorithm for photorealistic rendering. Thus, the current work is driven by a desire for a simple programming strategy (or recipe) that allows pre-existing ray tracing code to be parallelized on a heterogenous cluster of available office computers - strictly using open source components. Simplicity, stability, efficiency and modularity are the driving forces for this engineering project, and as such we do not claim any novel research contributions. However, we stress that this project grew out of a real-world need for a render cluster in our research group, and consequently our solutions have a significant practical value. In fact some of our results show a close to optimal speedup when considering the relative performances of each node. In this systems paper we aim at sharing these solutions and experiences with other members of the graphics community.

  • 12.
    Johansson Läthén, Gunnar
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Carr, Hamish
    School of Computer Science and Informatics, University College Dublin.
    Flexible and Topologically Localized Segmentation2007In: EuroVis07 Joint Eurographics: IEEE VGTC Symposium on Visualization / [ed] Ken Museth, Torsten Möller, and Anders Ynnerman, Aire-la-Ville, Switzerland: Eurographics Association , 2007, , p. 179-186p. 179-186Conference paper (Refereed)
    Abstract [en]

    One of the most common visualization tasks is the extraction of significant boundaries, often performed with iso- surfaces or level set segmentation. Isosurface extraction is simple and can be guided by geometric and topological analysis, yet frequently does not extract the desired boundary. Level set segmentation is better at boundary extrac- tion, but either leads to global segmentation without edges, [CV01], that scales unfavorably in 3D or requires an initial estimate of the boundary from which to locally solve segmentation with edges. We propose a hybrid system in which topological analysis is used for semi-automatic initialization of a level set segmentation, and geometric information bounded topologically is used to guide and accelerate an iterative segmentation algorithm that com- bines several state-of-the-art level set terms. We thus combine and improve both the flexible isosurface interface and level set segmentation without edges.

  • 13. Kirby, M
    et al.
    Lefohn, A
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Preusser, T
    Sapiro, G
    Whitaker, Ross
    Level Set and PDE Methods for Visualization2005Other (Other (popular science, discussion, etc.))
  • 14. Leforestier, C
    et al.
    Museth, Ken
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Response to Comments on: On the direct complex scaling of matrix elements expressed in a discrete va1998In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 109, p. 1203-1203Article in journal (Refereed)
  • 15.
    Ljung, Patric
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Lundström, Claes
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Transfer Function Based Adaptive Decompresion for Volume Rendering of Large Medical Data Sets2004In: Proceedings of IEEE/ACM Symposium on Volume Visualization 2004, Austin, USA, IEEE , 2004, p. 25-32Conference paper (Refereed)
    Abstract [en]

    The size of standard volumetric data sets in medical imaging is rapidly increasing causing severe performance limitations in direct volume rendering pipelines. The methods presented in this paper exploit the medical knowledge embedded in the transfer function to reduce the required bandwidth in the pipeline. Typically, medical transfer functions cause large subsets of the volume to give little or no contribution to the rendered image. Thus, parts of the volume can be represented at low resolution while retaining overall visual quality. This paper introduces the use of transfer functions at decompression time to guide a level-of-detail selection scheme. The method may be used in combination with traditional lossy or lossless compression schemes. We base our current implementation on a multi-resolution data representation using compressed wavelet transformed blocks. The presented results using the adaptive decompression demonstrate a significant reduction in the required amount of data while maintaining rendering quality. Even though the focus of this paper is medical imaging, the results are applicable to volume rendering in many other domains.

  • 16.
    Läthén, Gunnar
    et al.
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Carr, Hamish
    School of Computer Science and Informatics University College Dublin.
    Topologically Localized Level Set Segmentation2007In: Symposium on Image Analysis,2007, 2007, p. 89-92Conference paper (Other academic)
  • 17. Marker, J
    et al.
    Braude, I
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Breen, David
    Contour-Based Surface Reconstruction using Implicit Curve Fitting, and Distance Field Filtering2006In: IEEE Volume Graphics,2006, 2006, p. 95-Conference paper (Refereed)
  • 18.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Breen, David
    Whitaker, Ross
    Barr, A
    Level Set Surface Editing Operators2002In: ACM Transactions on Graphics, ISSN 0730-0301, E-ISSN 1557-7368, Vol. 21, no 3, p. 330-338Article in journal (Refereed)
  • 19.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Breen, David
    Zhukov, L
    Whitaker, Ross
    Level Set Segmentation from Multiple Non-Uniform Volume Datasets2002In: IEEE Visualization 02,2002, 2002, p. 179-Conference paper (Refereed)
  • 20.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Breen, D.E.
    Drexel University.
    Whitaker, R.T.
    University of Utah.
    Mauch, S.
    California Institute of Technology.
    Johnson, D.
    University of Utah.
    Algorithms for interactive editing of level set models2005In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 24, no 4, p. 821-841Article in journal (Refereed)
    Abstract [en]

    Level set models combine a low-level volumetric representation, the mathematics of deformable implicit surfaces and powerful, robust numerical techniques to produce a novel approach to shape design. While these models offer many benefits, their large-scale representation and numerical requirements create significant challenges when developing an interactive system. This paper describes the collection of techniques and algorithms (some new, some pre-existing) needed to overcome these challenges and to create an interactive editing system for this new type of geometric model. We summarize the algorithms for producing level set input models and, more importantly, for localizingminimizing computation during the editing process. These algorithms include distance calculations, scan conversion, closest point determination, fast marching methods, bounding box creation, fast and incremental mesh extraction, numerical integration and narrow band techniques. Together these algorithms provide the capabilities required for interactive editing of level set models. © The Eurographics Association and Blackwell Publishing Ltd 2005.

  • 21.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    D Billing, G
    Generalization of the MCTDH method to non-adiabatic systems1996In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 105, p. 9191-9191Article in journal (Refereed)
  • 22.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    D Billing, G
    Response to Comments on: Generalization of the MCTDH method to non-adiabatic systems1998In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 109, p. 351-351Article in journal (Refereed)
  • 23.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    D Billing, G
    Linderberg, J
    The full quantum mechanical three body problem of H2+1994In: Lecture Notes in Computer Science, Springer Verlag , 1994, p. 383-383Chapter in book (Other academic)
  • 24.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Kuppermann, A
    The asymptotic analysis of state-to-state tetraatomic reactions using row-orthonormal hyperspherical2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 115, no 1, p. 8285-8297Article in journal (Refereed)
  • 25.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Leforestier, C
    On the direct complex scaling of matrix elements expressed in a discrete variable representation. Ap1996In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 104, p. 7008-7008Article in journal (Refereed)
  • 26.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Lombeyda, S
    TetSplat: Real-Time Rendering and Volume Clipping of Large Unstructured Tetrahedral Meshes2004In: IEEE Visualization 04,2004, 2004, p. 433-Conference paper (Refereed)
  • 27.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    W Lo, M
    Barr, A
    Semi-immersive space mission design and visualization2001In: IEEE Visualization 01,2001, 2001, p. 501-Conference paper (Refereed)
  • 28.
    Museth, Ken
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Whitaker, Ross
    Breen, David
    Editing Geometric Models2003In: Geometric Level Set Methods in Imaging, Vision and Graphics / [ed] Stanley Osher; Nikos Paragios, New York: Springer Verlag , 2003, p. -510Chapter in book (Other academic)
    Abstract [en]

       Level set methods are emerging techniques for representing, deforming, and recovering structures in an arbitrary dimension across different fields (mathematics, fluid dynamics, graphics, imaging, vision, etc.). Advances in numerical analysis have led to computationally efficient tools for computing and analyzing interface motion within level set frameworks in a host of application settings. This authoritative edited survey provides readers with the state-of-the-art in applying level set techniques in the imaging, vision, and graphics domains, presenting thematically grouped chapters contributed by leading experts from both industry and academia. The work bridges the theoretical foundations of level set methods with the latest significant applications. It will assist readers with both the technical aspects of the field as well as its practical ramifications for areas like medical imaging, computer animation, film restoration, video surveillance, visual inspection, and a range of scientific and engineering disciplines. Topics and features: * Covers comprehensively the applications of imaging, vision, & graphics * Includes a helpful introductory survey chapter on level set methods * Provides a complete overview of concepts and advanced technologies in the field * Describes leading-edge research, providing insight into a variety of potential avenues for problem solving * Supplies numerous implementations, examples, and relevant and useful experimental results This essential resource carefully integrates the theoretical foundations of level set methods with their actual performance capabilities. Its clarity of organization and approach makes the book accessible for researchers and professionals working in the areas of vision, graphics, image processing, robotics, mathematics, and computational geometry

  • 29. Nakaguchi, T
    et al.
    Okui, M
    Tsumura, N
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Miyake, Y
    Segmentation of Pancreas from CT images Using Multiple Level Sets for Preoperative Simulation System2006In: IEICE Technical Committee on Medical Imaging,2006, 2006Conference paper (Refereed)
  • 30.
    Nielsen, M.B.
    et al.
    University of Århus, Arhus, Denmark.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Dynamic tubular grid: An efficient data structure and algorithms for high resolution level sets2006In: Journal of Scientific Computing, ISSN 0885-7474, E-ISSN 1573-7691, Vol. 26, no 3, p. 261-299Article in journal (Refereed)
    Abstract [en]

    Level set methods [Osher and Sethian. Fronts propagating with curvature-dependent speed: algorithms based on Hamilton-Jacobi formulations. J. Comput. Phys. 79 (1988) 12] have proved very successful for interface tracking in many different areas of computational science. However, current level set methods are limited by a poor balance between computational efficiency and storage requirements. Tree-based methods have relatively slow access times, whereas narrow band schemes lead to very large memory footprints for high resolution interfaces. In this paper we present a level set scheme for which both computational complexity and storage requirements scale with the size of the interface. Our novel level set data structure and algorithms are fast, cache efficient and allow for a very low memory footprint when representing high resolution level sets. We use a time-dependent and interface adapting grid dubbed the "Dynamic Tubular Grid" or DT-Grid. Additionally, it has been optimized for advanced finite difference schemes currently employed in accurate level set computations. As a key feature of the DT-Grid, the associated interface propagations are not limited to any computational box and can expand freely. We present several numerical evaluations, including a level set simulation on a grid with an effective resolution of 10243. © 2006 Springer Science+Business Media, Inc.

  • 31.
    Nielsen, Michael B.
    et al.
    University of Århus, Denmark.
    Nilsson, Ola
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Söderström, Andreas
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Out-of-core and compressed level set methods2007In: ACM Transactions on Graphics, ISSN 0730-0301, E-ISSN 1557-7368, Vol. 26, no 4, p. 16-Article in journal (Refereed)
    Abstract [en]

    This article presents a generic framework for the representation and deformation of level set surfaces at extreme resolutions. The framework is composed of two modules that each utilize optimized and application specific algorithms: 1) A fast out-of-core data management scheme that allows for resolutions of the deforming geometry limited only by the available disk space as opposed to memory, and 2) compact and fast compression strategies that reduce both offline storage requirements and online memory footprints during simulation. Out-of-core and compression techniques have been applied to a wide range of computer graphics problems in recent years, but this article is the first to apply it in the context of level set and fluid simulations. Our framework is generic and flexible in the sense that the two modules can transparently be integrated, separately or in any combination, into existing level set and fluid simulation software based on recently proposed narrow band data structures like the DT-Grid of Nielsen and Museth [2006] and the H-RLE of Houston et al. [2006]. The framework can be applied to narrow band signed distances, fluid velocities, scalar fields, particle properties as well as standard graphics attributes like colors, texture coordinates, normals, displacements etc. In fact, our framework is applicable to a large body of computer graphics problems that involve sequential or random access to very large co-dimension one (level set) and zero (e.g. fluid) data sets. We demonstrate this with several applications, including fluid simulations interacting with large boundaries (? 15003), surface deformations (? 20483), the solution of partial differential equations on large surfaces (˜40963) and mesh-to-level set scan conversions of resolutions up to ? 350003 (7 billion voxels in the narrow band). Our out-of-core framework is shown to be several times faster than current state-of-the-art level set data structures relying on OS paging. In particular we show sustained throughput (grid points/sec) for gigabyte sized level sets as high as 65% of state-of-the-art throughput for in-core simulations. We also demonstrate that our compression techniques out-perform state-of-the-art compression algorithms for narrow bands. © 2007 ACM.

  • 32. Nielsen, Michael
    et al.
    Nilsson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Söderström, Andreas
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Virtually Infinite Resolution Deformable Surfaces2006In: ACM SIGGRAPH ¿06 Sketches Applications,2006, 2006Conference paper (Refereed)
  • 33.
    Nilsson, Ola
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Breen, David
    Drexel University.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Surface Reconstruction Via Contour Metamorphosis: An Eulerian Approach With Lagrangian Particle Tracking2005In: IEEE Visualization 05,2005, IEEE , 2005, p. 407-414Conference paper (Refereed)
    Abstract [en]

    We present a robust method for 3D reconstruction of closed surfaces from sparsely sampled parallel contours. A solution to this problem is especially important for medical segmentation, where manual contouring of 2D imaging scans is still extensively used. Our proposed method is based on a morphing process applied to neighboring contours that sweeps out a 3D surface. Our method is guaranteed to produce closed surfaces that exactly pass through the input contours, regardless of the topology of the reconstruction.

    Our general approach consecutively morphs between sets of input contours using an Eulerian formulation (i.e. fixed grid) augmented with Lagrangian particles (i.e. interface tracking). This is numerically accomplished by propagating the input contours as 2D level sets with carefully constructed continuous speed functions. Specifically this involves particle advection to estimate distances between the contours, monotonicity constrained spline interpolation to compute continuous speed functions without overshooting, and stateof- the-art numerical techniques for solving the level set equations. We demonstrate the robustness of our method on a variety of medical, topographic and synthetic data sets.

  • 34.
    Nilsson, Ola
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Reimers, Martin
    University of Oslo, Norway .
    Museth, Ken
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Brun, Anders
    Uppsala University, Sweden .
    A NEW ALGORITHM FOR COMPUTING RIEMANNIAN GEODESIC DISTANCE IN RECTANGULAR 2-D AND 3-D GRIDS2013In: International journal on artificial intelligence tools, ISSN 0218-2130, Vol. 22, no 6Article in journal (Refereed)
    Abstract [en]

    We present a novel way to efficiently compute Riemannian geodesic distance over a two- or three-dimensional domain. It is based on a previously presented method for computation of geodesic distances on surface meshes. Our method is adapted for rectangular grids, equipped with a variable anisotropic metric tensor. Processing and visualization of such tensor fields is common in certain applications, for instance structure tensor fields in image analysis and diffusion tensor fields in medical imaging. The included benchmark study shows that our method provides significantly better results in anisotropic regions in 2-D and 3-D and is faster than current stat-of-the-art solvers in 2-D grids. Additionally, our method is straightforward to code; the test implementation is less than 150 lines of C++ code. The paper is an extension of a previously presented conference paper and includes new sections on 3-D grids in particular.

  • 35.
    Nilsson, Ola
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Reimers, Martin
    Department of Informatics, University of Oslo/Centre of Mathematics for Applications, University of Oslo.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Brun, Anders
    Centre for Image Analysis, Swedish University of Agricultural Sciences.
    Efficient computations of geodesic distanceManuscript (preprint) (Other academic)
    Abstract [en]

    We present a novel way to efficiently compute anisotropic distances over a tessellated domain in two dimensions. The method is based on an integral formulation of distance and entails solving a dynamic programming problem. We also present an intuitive geometric construction that is used to characterize dierent types of boundary conditions and show how they aect the resulting distance function in our and competing work.

    The included benchmark study shows that our method provides signicantly better results in anisotropic regions and is faster than a current stat-of-the-art solver. Additionally, our method is straightforward to code; the test implementation is less than 150 lines of C++ code.

  • 36. Reuterswärd, Kjell
    et al.
    Flynn, J
    Roble, D
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Model Flowing: Capturing and tracking of deformable geometry2005In: ACM SIGGRAPH 05, Sketches Applications,2005, 2005Conference paper (Refereed)
  • 37.
    Söderström, Andreas
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics . Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    A PML Based Non-Reflective Boundary for Free Surface Fluid Animation2010In: ACM Transactions on Graphics, ISSN 0730-0301, E-ISSN 1557-7368, Vol. 29, no 5, p. 136-Article in journal (Refereed)
    Abstract [en]

    This article presents a novel non-reflective boundary condition for the free surface incompressible Euler and Navier-Stokes equations. Boundaries of this type are very useful when, for example, simulating water flow around a ship moving over a wide ocean. Normally waves generated by the ship will reflect off of the boundaries of the simulation domain and as these reflected waves returns towards the ship they will cause undesired interference patterns.By employing a Perfectly Matched Layer (PML) approach we have derived a boundary condition that absorbs incoming waves and thus efficiently prevents these undesired wave reflections. To solve the resulting boundary equations we present a fast and stable algorithm based on the Stable Fluids approach. Through numerical experiments we then show that our boundaries are significantly more effective than simpler reflection preventing techniques. We also provide a thorough analysis of the parameters involved in our boundary formulation and show how they effect wave absorption efficiency.

  • 38.
    Söderström, Andreas
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    A Spatially Adaptive Morphological Filter For Dual-Resolution Interface Tracking Of Fluids2010Conference paper (Refereed)
    Abstract [en]

    We present a novel surface-tracking technique for free-surface fluid animations. Unlike the semi-implicit Particle Level Set method (PLS) our interface-tracking approach is purely implicit and hence avoids some of the well-known issues like surface noise and inflated memory footprints. Where PLS augments the interface with Lagrangian tracker-particles, we instead employ a higher resolution level set represented as a DT-Grid. The synchronization of our dual-resolution level sets is facilitated by a novel Spatially Adaptive Morphological (SAM) filter that attempts to preserve fine details while still avoiding spurious topology changes and boundary violations. We demonstrate that our approach can achieve comparative results to the PLS, but with a fraction of the memory footprint. We also show how our technique can be used to effectively enhance thin interface sheets at the cost of volume gain.

  • 39.
    Söderström, Andreas
    et al.
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Non-reflective boundary conditions for incompressible free surface fluids in SIGGRAPH 2009: Talks, SIGGRAPH 09, vol , issue , pp2009In: SIGGRAPH 2009: Talks, SIGGRAPH 09, New York: ACM , 2009Conference paper (Refereed)
    Abstract [en]

    We have developed a novel approach to open-boundaries for fluid animations. More specifically we present a highly efficient energy absorbing boundary condition for the incompressible Navier-Stokes equations in the prescence of a free surface. Our work extends and adapts a Perfectly Matched Layer (PML) approach [Berenger 1994; Johnson 2007], recently developed for the Navier-Stokes equations, to free surfaces in the context fluid animations. We show how our PML boundary condition is able to effectively eliminate reflections generated by the presence of solid boundaries in the simulation domain, and that our method is far superior to simpler approaches for reducing wave reflection. Furthermore, we have adapted our theoretical PML model to work with the Stable-Fluids Eulerian Navier-Stokes solver commonly used in computer graphics. Finally, we show that the cost of deploying our method in terms of memory and additional computations is small, and for a given quality significantly less than other known methods.

  • 40. Whitaker, Ross
    et al.
    Breen, David
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Segmentation of Biological Volume Datasets Using a Level Set framework2001In: Volume Graphics / [ed] Min Chen, Arie E. Kaufman, Roni Yagel, Vienna: Springer , 2001, p. 249-263Chapter in book (Other academic)
  • 41. Whitaker, Ross
    et al.
    Breen, David
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Soni, N
    A framework for Level Set segmentation of volumetric datasets2001In: IEEE Volume Graphics 01,2001, 2001, p. 159-Conference paper (Refereed)
    Abstract [en]

    This paper presents a framework for extracting surface models from a broad variety of volumetric datasets. These datasets are produced from standard 3D imaging devices, and are all noisy samplings of complex biological structures with boundaries that have low and often varying contrasts. The level set segmentation method, which is well documented in the literature, creates a new volume from the input data by solving an initial-value partial differential equation (PDE) with user-defined feature-extracting terms. Given the local/global nature of these terms, proper initialization of the level set algorithm is extremely important. Thus, level set deformations alone are not sufficient, they must be combined with powerful initialization techniques in order to produce successful segmentations. Our level set segmentation approach consists of defining a set of suitable pre-processing techniques for initialization and selecting /tuning different feature-extracting terms in the level set algorithm. This collection of techniques forms a toolkit that can be applied, under the guidance of a user, to segment a variety of volumetric data. Users can combine these methods in different ways and thereby access a wide range of functionalities, several of which are described in this paper and demonstrated on noisy volume data.

  • 42. Zhukov, L
    et al.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Breen, David
    Whitaker, Ross
    3D modeling and segmentation of Diffusion weighted MRI data2001In: SPIE Medical Imaging 01,2001, 2001, Vol. 4319, p. 401-412Conference paper (Refereed)
    Abstract [en]

    Diffusion weighted magnetic resonance imaging (DW MRI) is a technique that measures the diffusion properties of water molecules to produce a tensor-valued volume dataset. Because water molecules can diffuse more easily along fiber tracts, for example in the brain, rather than across them, diffusion is anisotropic and can be used for segmentation. Segmentation requires the identification of regions with different diffusion properties. In this paper we propose a new set of rotationally invariant diffusion measures which may be used to map the tensor data into a scalar representation. Our invariants may be rapidly computed because they do not require the calculation of eigenvalues. We use these invariants to analyze a 3D DW MRI scan of a human head and build geometric models corresponding to isotropic and anisotropic regions. We then utilize the models to perform quantitative analysis of these regions, for example calculating their surface area and volume.

  • 43. Zhukov, L
    et al.
    Museth, Ken
    Linköping University, Department of Science and Technology, Digital Media. Linköping University, The Institute of Technology.
    Breen, David
    Whitaker, Ross
    Barr, A
    Level Set Segmentation and Modeling of DT-MRI human brain data2003In: Journal of Electronic Imaging (JEI), ISSN 1017-9909, E-ISSN 1560-229X, Vol. 12, no 1, p. 125-133Article in journal (Refereed)
1 - 43 of 43
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