Fast Accurate Soft Shadows with Adaptive Light Source Sampling (original) (raw)
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Shadow generation has been subject to serious investigation in computer graphics, and many clever algorithms have been suggested. However, previous algorithms cannot render high quality soft shadows onto arbitrary, animated objects in real time. Pursuing this goal, we present a new soft shadow algorithm that extends the standard shadow volume algorithm by replacing each shadow quadrilateral with a new primitive, called the penumbra wedge. For each silhouette edge as seen from the light source, a penumbra wedge is created that approximately models the penumbra volume that this edge gives rise to. Together the penumbra wedges can render images that often are remarkably close to more precisely rendered soft shadows. Furthermore, our new primitive is designed so that it can be rasterized efficiently. Many real-time algorithms can only use planes as shadow receivers, while ours can handle arbitrary shadow receivers. The proposed algorithm can be of great value to, e.g., 3D computer games...
Axis-aligned filtering for interactive sampled soft shadows
ACM Transactions on Graphics, 2012
We develop a simple and efficient method for soft shadows from planar area light sources, based on explicit occlusion calculation by raytracing, followed by adaptive image-space filtering. Since the method is based on Monte Carlo sampling, it is accurate. Since the filtering is in image-space, it adds minimal overhead and can be performed at real-time frame rates. We obtain interactive speeds, using the Optix GPU raytracing framework. Our technical approach derives from recent work on frequency analysis and sheared pixel-light filtering for offline soft shadows. While sample counts can be reduced dramatically, the sheared filtering step is slow, adding minutes of overhead. We develop the theoretical analysis to instead consider axis-aligned filtering, deriving the sampling rates and filter sizes. We also show how the filter size can be reduced as the number of samples increases, ensuring a consistent result that converges to ground truth as in standard Monte Carlo rendering.
Soft shadow maps for linear lights
2000
Abstract. Soft shadows and penumbra regions generated by extended light sources such as linear and area lights are visual effects that significantly contribute to the realism of a scene. In interactive applications, shadow computations are mostly performed by either the shadow volume or the shadow map algorithm. Variants of these methods for soft shadows exist, but they require a significant number of samples on the light source, thereby dramatically increasing rendering times.
Soft Shadows From Extended Light Sources With Penumbra Deep Shadow Maps
Proceedings of Graphics …, 2005
This paper presents a new method of precomputing high-quality soft shadows that can be cast on a static scene as well as on dynamic objects added to that scene. The method efficiently merges the visibility computed from many shadow maps into a penumbra deep shadow ...