At first I saw the Wrap deformers as
possible stand-ins for muscle and bone, and modeled
them quite anatomically correct... but I soon
realized this deformer's influence zone is
too 'blurry' when set high enough to catch all
geometry around it, to be useful this way.
So I gradually modeled the Wraps closer and closer
in shape to the geometry they were deforming.
Until in the end, I simply copied the 0 level of it,
and set the influence zone down as low as I dared;
this seems to give the best control. But it
also means you have to make sure not to move any of
the 0-level verts relative to its Wrapper double,
because the first may easily end up outside of the
influence of the second (which ruins the whole
Keep in mind:
Model the surface according to your sketch and reference. You could start with a box, or a NURBS surface, it doesn't really matter, as long as you end up with a polygonal surface looking like your sketch. Use whatever poly-tools you're comfortable with. Also, o improve modeling you need to look at the real thing, I've found the best references here.
In this case I used a poly cylinder 8x17 (in fact 18 which I later found was one too many). Delete the top and bottom caps, Scale and Translate verts, first in the side view then front...
When you're done, if the edges don't run the way you need them to, use the Split Tool to create new edges, then delete the old edges. (Then delete any orphaned vertices, you don't need to be careful picking them, since only the orphaned ones can be deleted). Alternatively use "Delete Edge" from the "Edit Polygons" menu, this will automatically get rid of orphaned verts.
Since this topology is very important to the final result, you should take your time to fix things, don't rush on to the next stage. Also, you could theoretically use it as a basis for many other models.
IMPORTANT! NOW is the time to create your UV mapping.
When you're totally satisfied with the topology and UV's, convert to SubD one last time and start
editing on the higher levels. Remember: keep the
hierarchy (not the same as the history).
General advice for hierarchical SubD's:
Copy the SubD surface, and convert the copy (on the 0 level) back to a polygon. Name it 'Wrapper', name the SubD 'Skin'. Make a few more copies of Wrapper, move them aside. Create 3 layers, one for Skin, one for Wrapper, one for Morftargets. Name the targets appropriately, for instance in this case: KneeLeft1 and 2. Create a Blendshape, call it Bodytargets.
Smooth-Bind Wrapper to your skeleton (if you do this
before the Blendshapes you'll have to rearrange the
stack of deformations).
Create the Wrap, Skin is white, Wrapper is green, Max
Distance as small as you can make it - Apply.
Now when I go to frame 1 the deformations look like in the first example below, pretty damn crappy if I do say so myself... but still better than if you used a collapsed SubD or high res poly mesh bound directly to the skeleton.
Pull the slider for KneeLeft1 up to 1 and start
re-shaping the target. Keep it visible in the
orthogonal views, wireframe, keep the Skin in the
perspective view, smooth shaded.
Now the morf target looks like this:
You'll want to add more than one target to each knee. Now do the next target, maybe at around 130 degrees.
This one is trickier to get right - now the verts on the Wrapper geometry's thigh and calf are penetrating each other. And since Wrap deforming isn't based on a "one-on-one relationship between 2 verts" but more of a "whichever is closest will have the most effect", it gets harder to control their behavior as they clump together.
Next use Set Driven Key to hook these Blendshape sliders up to the Y-rotation of that knee. As the first slider reaches 1, the other stays at 0. As the second reaches 1 the first stays at 1, and if you have other targets, so on.
The hip usually needs 2 targets forward, and the spine maybe about 10 (left/right, back/front, lower/upper spine). The neck needs a few, and the shoulder needs about 4. All in all you should be able to make do with about 20 - 30, which is still very light and doesn't take that long to do.
If you want the knee to be even better than this you can either raise the resolution of the Wrapper - though there's a limit to how useful that can be, due to the 'fuzziness' of the influence area I mentioned earlier. You can also add Blendshapes straight to the high-res Skin, though I'd save that as a last resort - one such target makes the file much heavier than Wrapper targets. (Most of the other joints won't need this though.) Here's what the 90 and 130 degree rotations can look like with such fine-tuning:
Added benefits of this system: you can quickly, easily, and with little extra file-size, create targets to handle big sweeping changes to the geometry, which are typically very hard to do on very high-res geometry. You can then easily animate these changes. For instance, the character can very easily be made fatter or skinnier, or pregnant, or suddenly get Popeye arms etc. And you can do these things much later, it's very flexible and modular that way.
Also, if you hide the Skin the file is very fast and interactive and easy to animate - a built in low-res proxy.
Here's a screencap showing 3 different bodies, 2 descendants created from the original. Since they all have exactly the same topology on the 0 level, they can all be animated using the same Wrap deformer, which means there is no rigging time at all needed to switch between these 3, simply un-Wrap and re-Wrap.
The middle one is cut in 2 pieces, the seam is covered by a belt. The neck seams are covered by necklaces or collars.
Since Subd's are tricky to work with, why not use
poly meshes instead?
This shows how I lay out my Blendshapes - I overlap the ones that go together as a left-right pair, and place all for the same joint in the same row. In this example I'm using 3 consecutive targets for the knees.
Here are the hip targets.
The rest of the targets for this particular model (so
Best site for human reference photos: