Size conditioned visibility search system and method

Abstract

A system for performing visible object determination. Visualization software running on a host processor represents space with a hierarchy of cones, and generates a hierarchy of bounding hulls from a collection of objects by recursively grouping clusters of objects. Each hull node in the hull hierarchy stores parameters which characterize a bounding hull for the corresponding cluster or object. The visualization software searches the cone and hull hierarchies starting with the root cone and the root hull. Before exploring a given cone-hull pair, a normalized cone size for the cone and a normalized hull size for the hull may be computed, and the sizes compared. If the cone size is larger than the hull size, subcones of the cone are explored with respect to the hull. Conversely, if the hull size is larger than the cone size, subhulls of the hull are explored with respect to the cone.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 60 / 214,843 filed on Jun. 28, 2000 titled "Size Conditioned Visibility Search System and Method".[0002] 1. Field of the Invention[0003] The present invention relates generally to the field of computer graphics, and more particularly, to the problem of determining the set of objects (and portions of objects) visible from a defined viewpoint in a graphics environment.[0004] 2. Description of the Related Art[0005] Visualization software has proven to be very useful in evaluating three-dimensional designs long before the physical realization of those designs. In addition, visualization software has shown its cost effectiveness by allowing engineering companies to find design problems early in the design cycle, thus saving them significant amounts of money. Unfortunately, the need to view more and more complex scenes has outpaced the ability of graphics hardware systems to display them at reasonable frame rates...

AI Technical Summary

Benefits of technology

[0026] The dual-tree search may be illustrated in terms of a first cone of the cone tree structure and a first bound of the bound tree structure. The processor may compute a bound size for the first bound, and may compare the bound size to a cone size which corresponds to the first cone. If the bound size is larger than the cone size, the processor may search subbounds of the first bound with respect to the first cone. Conversely, if the cone size is larger than the bound size, the processor may search subcones of the first cone with respect to the first bound. A variety of methods are contemplated for computing the cone size and the bound size. By selecting the larger entity (first bound or first cone) for refinement, the visibility search method may, in some embodiments, prune the combined cone-bound tree more effectively, and determine the set of visible objects with increased efficiency.

Problems solved by technology

These queries however are more expensive than the queries used in the ray casting method.

A sloppy algorithm could end up wasting most of the computational advantage provided by improvements in the dual tree search.

However, the visibility search of a cone hierarchy which is refined to pixel resolution is computationally expensive.

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