An improved illumination model for shaded display
Communications of the ACM
Approximate soft shadows on arbitrary surfaces using penumbra wedges
EGRW '02 Proceedings of the 13th Eurographics workshop on Rendering
IEEE Computer Graphics and Applications
SIGGRAPH '84 Proceedings of the 11th annual conference on Computer graphics and interactive techniques
A geometry-based soft shadow volume algorithm using graphics hardware
ACM SIGGRAPH 2003 Papers
Soft shadow volumes for ray tracing
ACM SIGGRAPH 2005 Papers
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One of the best choices of multimedia for fast, high quality shadows is the shadow volume algorithm. However, the calculation of detailed soft shadows is one of the most difficult challenges in computer graphics in the case of area light source. In this paper, we present a new fast trapeziums-based algorithm for rendering soft shadows using a single shadow ray for each shadow pixel. Compared to other soft shadow methods, our algorithm produces very pleasing smooth and artifact-free soft shadow image while executing one order of magnitude faster. Our main contribution is a trapeziums-based method for quickly determining the proportion of area light which overlaps with occluders as seen from the shadow point to be shaded rather than using sample points on the area light source. To speed up calculation a bound box of projected light source is used to relate potential silhouette edges with shadow points beforehand. We demonstrate results for various scenes, showing that detailed soft shadows can be generated at very high speed.