What is 3D volume rendering?
While surface rendering creates 3D models with surface polygons and triangles, 3D volume rendering creates a 3D display from the voxels directly. Object boundaries are used to include or exclude image volume in the rendering process. The volume rendering displays voxel intensity in 3D space. With the 3D Rendering/Split Object command, you can cut object into smaller pieces and then use volume rendering to show the volume. The process of creating volume rendering is similar to surface rendering.