  Volume rendering always plays an important role in the field of medical
imaging and industrial design. In recent years, the realistic and interactive
volume rendering of the global illumination can improve the perception of shape
and depth of volumetric datasets. In this paper, a novel and flexible
performance method of slice-based ray casting is proposed to implement the
volume illumination effects, such as volume shadow and other scattering
effects. This benefits from the slice-based illumination attenuation buffers of
the whole geometry slices at the viewpoint of the light source and the
high-efficiency shadow or scattering coefficient calculation per sample in ray
casting. These tests show the method can obtain much better volume illumination
effects and more scalable performance in contrast to the local volume
illumination in ray casting volume rendering or other similar slice-based
global volume illumination.
