Abstract: A method renders an object including multiple volumes and polygons. The method casts a ray through the object for each pixel of an image. Each rays is partitioned into segments according to surfaces of each volume. Color and opacity values are accumulated for each segment of each ray. Starting depths of each segment are merged and sorted, in an ascending order, into a combined depth list. Consecutive pairs of starting depths are taken to perform the following steps until done. A front clip plane and a back clip plane are defined for each pair of starting depths. Polygons between the front clip plane and a next volume surface are composited, voxels between the front clip plane and the back clip plane are composited, and polygons between the next volume surface and the back clip plane are composited.