A fast shadow algorithm for area light sources using backprojection
SIGGRAPH '94 Proceedings of the 21st annual conference on Computer graphics and interactive techniques
The depth discontinuity occlusion camera
I3D '06 Proceedings of the 2006 symposium on Interactive 3D graphics and games
Real-time soft shadow mapping by backprojection
EGSR'06 Proceedings of the 17th Eurographics conference on Rendering Techniques
Sample based visibility for soft shadows using alias-free shadow maps
EGSR'08 Proceedings of the Nineteenth Eurographics conference on Rendering
| Hi-index | 0.00 |
Soft shadows are crucial for computer generated imagery, as they increase the level of realism and improve spacial perception. Generating soft shadows is inherently difficult because it involves evaluating the visibility between an area light source and every point in the scene. One way to accurately compute this visibility is to backproject occluder geometry onto the light for every point in the scene. However, searching for relevant edges is costly so backprojection scales poorly with increased scene complexity. We present an interactive soft shadow algorithm that draws insight from the depth discontinuity occlusion camera model (DDOC) [Popescu and Aliaga 2006], a non-pinhole camera that bends light rays near discontinuity edges to sample normally hidden surfaces. By carefully choosing the size of DDOC distortion regions based on light and occluder geometry, we generate a map that stores the closest silhouette edges for each pixel. This enables us to find the most relevant edge to backproject using a single map lookup and additional edges with a small neighborhood search. Our method combines the accuracy of object-space backprojection methods with the efficiency of an image-based approach.