Patent ID: 7817823

Claim:
A method, comprising: generating a penumbra map including shadow information regarding a plurality of pixels of a shadow acceptor, wherein the shadow information includes for each of the plurality of pixels, a distance from a light source to a point on a shadow caster along a line traveled by light from the light source to the respective pixel, wherein the respective distance for each of the plurality of pixels indicates whether the pixel is in a shadow formed by attenuation of light from an area light source by a shadow caster onto the shadow acceptor; for each respective one of the plurality of pixels: calculating a radius for a filter for each of the plurality of pixels based on the shadow information in the penumbra map for the respective pixel, wherein the radius calculated for one of the pixels is different from the radius for a different one of the pixels; applying the filter to the shadow information for one or more of the plurality of pixels to determine shadow density for the respective pixel, wherein the one or more of the plurality of pixels are within the calculated radius from the respective pixel; and using the shadow density for the respective pixel in one or more lighting calculations to render the respective pixel.