Anti-aliased Soft Shadows

Publications info:
Valient, M., “Hardware Generated Object Silhouettes“. G – Journal for Geometry and Graphics, No 3, Volume 2, Slovak Society for Geometry and Graphics, 2005, ISSN 1336-524X.

Valient, M., Bujnak, T., “GPU Friendly, Anti-aliased, Soft Shadow Mapping“. Reviewed poster. ACM Proceedings of SCCG 2005, ACM Press, October 2005, ISBN 1-59593-203-6.

How are these articles related:
The first article (Hardware Generated Object Silhouettes) describes in depth the possibility to generate object silhouettes on GPU and the second article (GPU Friendly, Anti-aliased, Soft Shadow Mapping) uses this approach to generate the soft shadows.

Abstract (Hardware Generated Object Silhouettes):
In this article, we present a high performance algorithm that renders thick object silhouettes completely on the GPU using only two passes. We present a new structure called topology aware mesh, which allows us to overcome the lack of global adjacency information during the
vertex processing on GPU. Topology aware mesh stores complete face adjacency information for each vertex and allows edge computations to be performed on graphics hardware. Topology aware mesh consumes about 0.77 times the storage of the original mesh when using 16-bit precision and stream frequency capability of current hardware and it is created only once during the linear-time pre-processing step. Our approach can be used as a replacement for many CPU based silhouette detection algorithms in NPR or shadow rendering.

Abstract (GPU Friendly, Anti-aliased, Soft Shadow Mapping):
In this paper, we present an algorithm that renders anti-aliased, soft edged shadows using a modified shadow-mapping approach. Our algorithm adds the silhouette information to the shadow map, thus allowing rendering precise and continuous shadow boundaries. Soft shadows for small spherical light sources are rendered using a variation of the percentage closer filtering algorithm [Reeves 1987]. The critical improvement of our algorithm over previous approaches is that it runs completely on the GPU using only two passes. This includes the silhouette detection step which is done completely in the vertex and pixel shaders using specially generated version of the mesh.

Download the ‘Hardware Generated Object Silhouettes’
Download the ‘GPU Friendly, Anti-aliased, Soft Shadow Mapping’