Efficient Shadows for GPU-based Volume Raycasting

GPU-based raycasting has emerged as the defacto standard for interactive volume rendering on off-the-shelf graphics hardware. Even though in theory this technique can be easily extended by shadow feelers in order to support shadows, this obvious approach has a major impact on the rendering performance. In this paper we will investigate shadowing extensions for GPU-based volume raycasting and compare them with respect to their quality and their performance. In particular, we will consider shadow rays, shadow mapping and deep shadow maps, For these techniques we will address their implementations using current graphics boards, and we will compare their visual results as well as their runtime behavior.