Summary: Efficient Image-Based Methods for Rendering Soft Shadows
Pixar Animation Studios
Alan Heirich Laurent Moll
Compaq Computer Corporation
Figure 1: A plant rendered using our interactive layered attenuation-map approach (left), rayshade (middle), and our efficient high-quality coherence-based
raytracing approach (right). Note the soft shadows on the leaves. To emphasize the soft shadows, this image is rendered without cosine falloff of light intensity.
Model courtesy of O. Deussen, P. Hanrahan, B. Lintermann, R. Mech, M. Pharr, and P. Prusinkiewicz.
We present two efficient image-based approaches for computation
and display of high-quality soft shadows from area light sources.
Our methods are related to shadow maps and provide the associ-
ated benefits. The computation time and memory requirements for
adding soft shadows to an image depend on image size and the
number of lights, not geometric scene complexity. We also show
that because area light sources are localized in space, soft shadow
computations are particularly well suited to image-based render-
ing techniques. Our first approach--layered attenuation maps--