UC San Diego

Light propagation volumes is a real-time single bounce indirect lighting approximation that uses spherical harmonics for light representation and a grid-based light transport. The technique is useful for applying indirect light to participating media, glossy specular reflection, and indirect diffuse illumination, but this thesis focuses on the indirect diffuse illumination. When applying indirect diffuse light, the light propagation volume method has issues with light bleeding, self lighting, and surface lighting artifacts. Also, when the indirect diffuse lighting is applied to more complex geometry, there is a lack of directional influence in the shading, producing a flat lighting effect, uncharacteristic of diffuse shading. I modify the light propagation volume approach by extending the spherical harmonics from two bands to three bands and describe a higher order propagation approach that considers 26 directions of propagation versus the original six. The new resulting technique is called higher order light propagation volumes. Higher order light propagation volumes are able to combat some of the problems present with light propagation volumes. The new technique reduces the appearance of lighting artifacts, and at the same time promotes a light distribution in scenes that resembles reference implementations, such as path tracing. Lastly, indirect diffuse illumination applied with the new technique produces higher quality diffuse shading detail because the directional representation of light is better preserved with the combination of extended spherical harmonics light representation and the higher order propagation method