Precomputed Illumination for Virtual Reality Scenarios

In this work we present a lightweight and easy to implement approach to enhance static scenes with diffuse surfaces and local light sources by soft shadows and indirect illumination based on precomputed radiance transfer (PRT). Targeting the easy integration of global illumination effects into existing virtual reality applications, we compared recent PRT based approaches concerning their efficiency and fast implementability. We developed orthonormal bases for the representation of both precomputed indirect illumination and precomputed visibility using PCA of example data yielding a high compression ratio and fast reconstruction of precomputed data. Unlike most comparable approaches featuring local area and point light sources we do not rely on shadow mapping or stencil shadows in order to determine the direct lighting, although we do not limit the light source to hemispherical directions of a shaded surface point. Further, we apply a meshless basis construction to avoid typical problems when tesselating a given scene.