EG 2013 - Short Papers

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/300

Browse

Browsing EG 2013 - Short Papers by Subject "Computational Geometry and Object Modeling"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Accelerating kd-tree Searches for all k-nearest Neighbours
    (The Eurographics Association, 2013) Merry, Bruce; Gain, James; Marais, Patrick; M.- A. Otaduy and O. Sorkine
    Finding the k nearest neighbours of each point in a point cloud forms an integral part of many point-cloud processing tasks. One common approach is to build a kd-tree over the points and then iteratively query the k nearest neighbors of each point. We introduce a simple modification to these queries to exploit the coherence between successive points; no changes are required to the kd-tree data structure. The path from the root to the appropriate leaf is updated incrementally, and backtracking is done bottom-up. We show that this can reduce the time to compute the neighbourhood graph of a 3D point cloud by over 10%, and by up to 24% when k
  • Thumbnail Image
    Item
    Automatic Generation of Constructable Brick Sculptures
    (The Eurographics Association, 2013) Testuz, Romain; Schwartzburg, Yuliy; Pauly, Mark; M.- A. Otaduy and O. Sorkine
    Fabrication of LEGO R models in large scale requires careful pre-planning to produce constructable and stable models. We propose a system that, starting with a voxelization of a 3D mesh, merges voxels to form larger bricks, and then analyzes and repairs structural problems, finally outputting a set of building instructions. We also present extensions such as producing hollow models, fulfilling limits on the number of bricks of each size, and including colors. Results (both real and virtual) and timings show significant improvements over previous work.
  • Thumbnail Image
    Item
    Direct Contouring of Implicit Closest Point Surfaces
    (The Eurographics Association, 2013) Auer, Stefan; Westermann, Rüdiger; M.- A. Otaduy and O. Sorkine
    Constructing a (signed) distance field and contouring its zero level set are two important steps in many surface reconstruction methods. While most high-quality distance transforms compute the distance to the surface as well as the closest point on it, the contouring step typically uses only the distance and omits the closest point information. Our novel closest point contouring algorithm (CPC) uses the full closest point field, and, thus, allows improving existing methods for high-quality triangle mesh reconstruction based on implicit function models: Since we select the vertex positions directly from the set of closest points, all triangle vertices are guaranteed to lie exactly on the zero-contour and no approximations are necessary. By employing recent findings in the context of so-called embedding techniques, we derive a formulation of the mean curvature vector on the closest point representation and use this formulation to properly select the vertices to be triangulated. In combination with a new table-based triangulation scheme this allows us to detect and preserve sharp features, and to avoid small degenerated triangles in smooth areas. CPC can handle open and non-orientable surfaces, and its data-parallel nature makes it well suited for GPUs.
  • Thumbnail Image
    Item
    A Segmentation Transfer Method for Articulated Models
    (The Eurographics Association, 2013) Elghoul, Esma; Verroust-Blondet, Anne; M.- A. Otaduy and O. Sorkine
    In this paper, we propose using a pre-segmented example model to perform semantic-oriented segmentation of non-rigid 3D models of the same class (human, octopus, quadrupeds, etc.). Using the fact that the same type of non-rigid models share the same global topological structure, we exploit coarse topological shape attributes in conjunction with a seed-based segmentation approach to transfer a meaningful and consistent segmentation from the example to the target models. Promising results of inter-shape segmentation transfer are shown and discussed for different classes of models.
  • Thumbnail Image
    Item
    Transfinite Surface Patches Using Curved Ribbons
    (The Eurographics Association, 2013) Várady, Tamás; Salvi, Péter; Rockwood, Alyn; M.- A. Otaduy and O. Sorkine
    An important problem in Computer Aided Design is to create digital representations for complex free-form objects that produce nice, predictable shapes and facilitate real-time editing in 3D. The clue to curve network-based design is the construction of smoothly connected multi-sided patches. A new type of transfinite surface, called Composite Ribbon (CR) patch is introduced, that is a combination of curved ribbons and ensures G1 continuity over non-regular, convex polygonal domains. After discussing the construction and the preferred parameterization scheme, a few simple examples conclude the paper.
  • Thumbnail Image
    Item
    Volume Controllable SPH
    (The Eurographics Association, 2013) Shinkawa, Masanori; Kawaguchi, Yoichiro; M.- A. Otaduy and O. Sorkine
    We extend a Predictive Corrective Incompressible SPH (PCISPH) algorithm to a volume controllable SPH algorithm. In order to handle volume changes, we develop a method to control fluid volume. Our method precomputes a pressure correction factor of PCISPH at various particle volume and interpolates these factors to get a factor for arbitrary particle volume. Thanks to a PCISPH's high correctiveness, our method enables both stiff volume contraction and expansion. Additionally we derive computations for density and a force by pressure to prevent instabilities and unnatural flocks near interfaces between two fluids with different particle volume. Furthermore, granular simulators based on fluid simulators are also extensible to simulate volume change of granular materials.