ABSTRACT
This work presents a new technique for the real-time rendering of shadows with penumbrae based on shadow mapping. The method uses a screen-aligned texture that contains the distance between the shadow and its potential occluder. This information is used to set up the size of an anisotropic Gaussian filter kernel applied in screen space, which smoothens the standard shadows to create the penumbra. Given that a Gaussian filter is separable, the number of samples required to create the penumbra is much lower than in other soft shadowing approaches. In consequence, higher performance is obtained while also allowing perceptually correct penumbrae to be represented.
