Multiresolution hierarchies for multimodal interaction in virtual environments.

摘要

Interactive visualization of large geometric datasets in computer graphics is a challenging task due to several reasons. One of the main reasons is that the sizes of most present-day geometric datasets are one or more orders of magnitude larger than what the current graphics hardware can display at interactive rates.; Genus Simplification is a topology-simplifying approach that can be used for genus reductions, removal of protuberances, and repair of cracks in polygonal models in a unified framework. This work is complementary to the existing work on geometry simplification of polygonal datasets and we found that using topology and geometry simplifications together yields superior multiresolution hierarchies than is possible by using either of them alone.; We have developed an algorithm for performing adaptive real-time level-of-detail-based rendering for triangulated polygonal models. The simplifications are dependent on viewing direction, lighting, and visibility and are performed by taking advantage of image-space, object-space, and frame-to-frame coherences.; Topology simplification is essential to achieve aggressive reduction on the number of triangles for objects that are far from the view. Therefore, we have developed a technique for performing view-dependent geometry and topology simplifications for level-of-detail-based renderings of large models. The algorithm proceeds by preprocessing the input dataset into a binary view-dependence tree of vertex-pair collapses.; View-dependent simplification techniques have not been able to take full advantage of the underlying graphics hardware such as triangle strips. View-dependent rendering suffer from this drawback because the triangle mesh connectivity changes at every frame we propose. Skip Strip as a novel data-structure that efficiently maintains triangle strips during view-dependent changes. A Skip Strip stores the vertex hierarchy nodes in a skip-list-like manner with path compression.; To take advantage of the widespread availability of parallel machines, we have developed a parallel algorithm for preprocessing as well as real-time navigation of view-dependent virtual environments on shared memory multiprocessors.; For richer virtual environment, haptic display with force feedback is essential. But most of the present haptic systems are only capable of representing a few hundreds of geometric primitives. To enable haptically rendering of large datasets we introduce Perception Dependent Haptic Rendering, a novel approach to reduce the complexity of the rendered dataset, which is based on the View-Dependence Tree. (Abstract shortened by UMI.)