Institute for Data Analysis and Visualization

Pre-integrated volume rendering is an effective technique for generating high-quality visualizations. The precomputed lookup tables used by this method are slow to compute and can not include truly pre-integrated lighting due to space constraints. The lighting for pre-integrated rendering is therefore subject to the same sampling artifacts as in standard volume rendering. We propose methods to speed up lookup table generation and minimize lighting artifacts. The incremental subrange integration method we describe allows interactive lookup table generation in O(n2) time without the need for approximation or hardware assistance. The interpolated preintegrated lighting algorithm eliminates discontinuities by linearly interpolating illumination along the view direction. Both methods are applicable to any pre-integrated rendering method, including cell projection, ray casting, and hardware-accelerated algorithms.