One of the fundamental problems in computer graphics is generating accurate soft shadows from area light sources. Soft shadows provide valuable cues about the relationships between objects, becoming sharper near the casting object and more blurry (softer) further away. PCSS builds upon regular shadow mapping. It does this by shading each pixel in camera space, and then computing the penumbra size by analysing the average distance to occluded objects.

LOW Shadows MEDIUM Shadows HIGH Shadows PCSS PCSS Ultra
The two images on the left have hard, unrealistically sharp shadows while with NVIDIA PCSS images show shadows that are softer and much more accurate.


This technique provides excellent visual results, particularly for realistically textured scenes, while maintaining a high degree of interactivity and realism. Advanced Soft Shadows provides a simple interface for adding high quality efficient shadows to games. It improves on PCSS to reach new levels of quality and performance, with the ability to render cascaded shadow maps, and multiple spot lights.