  Sample based ray marching is an effective method for direct volume rendering
of unstructured meshes. However, sampling such meshes remains expensive, and
strategies to reduce the number of samples taken have received relatively
little attention. In this paper, we introduce a method for rendering
unstructured meshes using a combination of a coarse spatial acceleration
structure and hardware-accelerated ray tracing. Our approach enables efficient
empty space skipping and adaptive sampling of unstructured meshes, and
outperforms a reference ray marcher by up to 7x.
