Architecture of the Process-Parallel Algorithm: This figure highlights different components of our hybrid shadow generation algorithm. Each color represents a separate graphics processor or CPU.
We present a new algorithm for interactive generation of hard-edged, umbral shadows in complex environments with a moving light source. Our algorithm is based on a hybrid approach that combines some of the efficiencies of image-precision techniques along with the image quality of object-precision methods. We present interactive algorithms based on levels-of-detail (LODs) and visibility culling to compute the potential shadow-casters and shadow-receivers. We further reduce their size based on a novel cross-visibility culling algorithm. Finally, we use a combination of shadow polygons and shadow maps to generate shadows. We also present techniques for LOD-selection that eliminate the artifacts in self-shadows. Our algorithm can generate sharp shadow edges and reduce aliasing. We have implemented the algorithm on a three PC system with NVIDIA GeForce-4 cards and applied it to three complex environments composed of millions of triangles. It can render the scene and generate shadows at 7-25 frames per second on these models.
|The left image shows a snapshot generated from the application of our hybrid shadow generation algorithm to the power plant model (12.7M triangles). The middle image shows a different viewpoint generated using perspective shadow maps. Notice the aliasing artifacts. The right image highlights the shadows generated by our interactive algorithm from the same viewpoint with sharper boundaries.|
UNC Walkthru Group
CB #3175, Department of Computer Science
University of North Carolina
Chapel Hill, NC 27599-3175