Real-time Radiance Caching using Chrominance Compression

Figure 1. Our method retains the directional resolution of the luminance component of a radiance field, while suppressing the chrominance (left). This leads to efficient radiance cache throughput, while preserving details such as indirect shadows (middle). High compression can be exploited in the real-time rendering of large or detailed environments (right). This paper introduces the idea of expressing the radiance field in luminance/chrominance values and encoding the directional chrominance in lower detail. Reducing the spherical harmonics coefficients for the chrominance components allows the storage of luminance in higher order spherical harmonics in the same memory budget resulting in finer representa-tion of intensity transitions. We combine the radiance field chrominance compression with an optimized cache population scheme, by generating cache points only at locations, which are guaranteed to contribute to the reconstructed surface irradiance. These computation and stor-age savings allow the use of higher-order spherical harmonics representation to sufficiently capture and reconstruct the directionality of diffuse irradiance, while maintaining fast and customizable performance. We exploit this radiance representation in a low-cost real-time radiance caching scheme, with support for arbitrary light bounces and view-independent indi-rect occlusion and showcase the improvements in highly complex and dynamic environments. Furthermore, our general qualitative evaluation indicates benefits for offline rendering appli-cation as well