Surface rendering is limited in that it will display only surfaces that meet a threshold density, and will display only the surface that is closest to the imaginary viewer. In contrust, In volume rendering, transparency, colors and shading are used to allow a better representation of the volume to be shown in a single image.

For example, the bones of the pelvis could be displayed as semi-transparent, so that, even at an oblique angle, one part of the image does not conceal another.