Fast Walkthroughs with Image Caches and Ray Casting

Michael Wimmer, Markus Giegl, Dieter Schmalstieg 1999 Eurographics Workshop on Virtual Environments [Extended Version TR-186-2-98-30]


We present an output-sensitive rendering algorithm for accelerating walkthroughs of large, densely occluded virtual environments using a multi-stage Image Based Rendering Pipeline. In the first stage, objects within a certain distance are rendered using the traditional graphics pipeline, whereas the remaining scene is rendered by a pixel-based approach using an Image Cache, horizon estimation to avoid calculating sky pixels, and finally, ray casting. The time complexity of this approach does not depend on the total number of primitives in the scene. We have measured speedups of up to one order of magnitude.

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Funding: Austrian Science Foundation  under contract no. P-11392-MAT and Ars Creat Game Development.
Contact: Michael Wimmer, Markus Giegl, Dieter Schmalstieg


www_bluehorizon.jpg (98099 bytes) Ray casting is used to cover the pixels of the Far Field (beyond 100m). Pixels above the horizon are culled early
www_topview.jpg (98757 bytes) A view over much of the virtual city that was used for the walkthroughs
www_farfieldborder.jpg (79531 bytes) A typical view from a walkthrough sequence in the city