Carrying on! After we’ve created a low-poly volume, and laid out its polygons on an additional uv coordinate table like a skinned cat, we can bake the displacement map. This takes each point on the mesh corresponding to a pixel and assigns it a grey value in accordance with the its distance to the high-resolution mesh. This information looks like this (the layout is not the best – a result of my hacked out uv map for an unfinished model – resulting in lots of wasted pixels):
As you can see from the animated gif, the result is very accurate.
But… what’s the purpose?
The main advantage is memory efficiency. The base mesh of ~26mb is reduced to one of just over 108 kb and a 137kb jpg (1024×1024). Not only storage is more efficient, but imaging a 3D model from this might require considerably reduced computational power, while allowing for dynamic resolution based on camera distance. In other words, if a scientist needs to compare meshes for volumes, this might present a technique to provide quantitatively accurate models which can be analyzed much more quickly at various levels of detail, and be used afterward in interactive digital publications as navigable illustrations with low computational overhead. And of course, this can be done for any 3D mesh… whether it represent bone, muscle or air pockets.
From the point of the artist, creating such a mesh is like sketching from a life model. I have a much better understanding of a crocodile’s cranial morphology after doing this, as if I’ve copied the drawings of a master. It is a good deal of work (more than I initially estimated), but well worth it.