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Now showing 1 - 3 of 3
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    A Haptic System for Drilling into Volume Data with Polygonal Tools
    (The Eurographics Association, 2009) Liu, Yu; Laycock, Stephen D.; Wen Tang and John Collomosse
    With the developments of volume visualization technology for complex data sets comes new challenges in terms of user interaction and information extraction. Volume haptics has proven itself to be an effective way of extracting valuable information by providing an extra sense from which to perceive three dimensional data. This paper presents a haptic system for using arbitrary polygonal tools for drilling into volume data. By using this system, users can select from a variety of virtual tools to gain continuous and smooth force feedback during the drilling of volumetric data. As the user manipulates the haptic device the tool typically only moves a small amount. By considering the locations of the data points, that are modified when drilling, a relatively small number of voxels are determined each frame which must be recomputed by a Marching Cubes algorithm.
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    An Edge-based Approach to Adaptively Refining a Mesh for Cloth Deformation
    (The Eurographics Association, 2009) Simnett, Timothy J. R.; Laycock, Stephen D.; Day, Andy M.; Wen Tang and John Collomosse
    Simulating cloth in real-time is a challenging endeavour due to the number of triangles necessary to depict the potentially frequent changes in curvature, in combination with the physics calculations which model the deformations. To alleviate the costs, adaptive methods are often employed to refine the mesh in areas of high curvature, however, they do not often consider a decimation or coarsening of areas which were refined previously. In addition to this, the triangulation and consistency checks required to maintain a continuous mesh can be prohibitively time consuming when attempting to simulate larger pieces of cloth. In this paper we present an efficient edge-based approach to adaptively refine and coarsen a dynamic mesh, with the aim to exploit the varied nature of cloth by trading the level of detail in flat parts for increased detail in the curved regions of the cloth. An edge-based approach enables fast incremental refinement and coarsening, whereby only two triangles need updating on each split or join of an edge. The criteria for refinement includes curvature, edge length and edge collisions. Simple collision detection is performed allowing interactions between the cloth and the other objects in the environment.
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    A Distance Hierarchy to Detect Collisions Between Deformable Objects
    (The Eurographics Association, 2007) Madera, Francisco A.; Day, Andy M.; Laycock, Stephen D.; Ik Soo Lim and David Duce
    To detect collisions between deformable objects we introduce an algorithm that computes the closest distances between certain feature points defined in their meshes. The strategy is to divide the objects into regions and to define a representative vertex that serves to compute the distance to the regions of the other objects. Having obtained the closest regions between two objects, we proceed to explore these regions by expanding them and detecting the closest sub-regions. We handle a hierarchy of regions and distances where the first level contains n1 regions, each one is divided into n2 sub-regions, and so on. A collision is obtained when the distance between two vertices in the last level of the tree is less than a predefined value e. The advantage of our algorithm is that we can follow the deformation of the surface with the representative vertices defined in the hierarchy.