For example:
- Hold your arm out and bend your elbow; you should see that bending your elbow adds a small flex to you bicep.
- This happens automatically because, in order to bend your elbow, the biceps muscles must contract and this makes them look bigger.
- The same thing happens to your calf muscles when you bend your knee or foot.
- This happens to a lot of muscles and in a living creature it's automatic.
- This is NOT automatic in 3D figures because they're not alive and they don't have muscles; they're just mathematics and geometry inside a computer.
Most high-end 3D software (Maya, Lightwave, Z-Brush) has supported weight mapping for a while, and even some of the consumer-end stuff (Daz Studio & Poser) has had limited support for it in the newer figure ranges, particularly Daz3D's Genesis 3 & 8.
Unfortunately, Poser (which is the backbone of my 3D illustration process) does not easily support the Genesis figures. This means that, essentially, I'm "stuck" with using Victoria 4 and Michael 4 (and earlier) figures in my work.
Now, although Victoria 4 and Michael 4 are fantastic figures that are still full of life (especially for my comics work that doesn't require animation or 100% photo realism), they do feel a bit "long in the tooth" when it comes to things like weight mapping. Instead of having smart rigs that know how to flex muscles automatically when bending leg or arm, you have to do those modifications manually.
Fortunately, some really smart people created the scripts and info needed to apply weight mapping to Victoria 4 (hopefully Michael 4 will be soon behind, but I doubt it as the guys just don't get the love that the women do).
The V4 WM resources can be downloaded at this location:
http://www.morphography.uk.vu/~cagepage/poserplace/poserplace.html