The Extended version of Adobe Photoshop is: 1.) too expensive for most people, and 2.) capable of importing and exporting 3D objects, which is fairly mind-blowing for a "paint program"! Our friend Welles Goodrich showed Gary the results of experimenting with some preset shapes in PS CS5 Extended along with custom depth maps he created, and it was just too amazing and far too much fun not to share with our members. Here’s the scoop, tutorial-style:

Depth Maps and “Pushing” a Surface

If you use and have a moderate understanding of the features in many modeling programs (such as 3D Studio, Poser, C4D, Lightwave, or others), you’ll have hit upon the displacement map function. Adobe calls this a depth map in Photoshop’s 3D features, different term, same effect. A displacement map changes the surface of a model’s mesh at rendering time.

You paint or otherwise create a grayscale bitmap image, and then tell your modeling program to use this bitmap as the surface material of your model’s mesh. Based on the brightness value (usually on a scale from black=0 to white=255), under any given pixel in the bitmap, the underlying geometry of the mesh is pulled (white pulls) a distance away from the true surface, or it’s pushed into the surface (black pushes). Here’s a visual example of the depth map (displacement map) when applied to a cylinder, a sphere, and to a plane: