Modeling for rigging
Good, fast and clean Deformations are 30% joint placement and 70% the modeling!!!
(B. Clark)
Basics
When modeling, or checking out someone else's model for rigging, always, ALWAYS throw a very quick skeleton in to check to see where the joints will be placed. Even if it looks perfect from eyeballing, there is something that you, if you are me, are missing. Will save a lot of trouble down the line.
-Avoid stars (ie. five or more pointed structures where your edge flows meet. If you have to have them, put them in areas you will not see and/or areas that don't have a lot of motion. Try to keep everything in quads, as this will make it easier for the edges to collapse and expand into each other.
-For best deformation, the character should have edge loops that follow the curves of its natural skeletal structure and musculature. See below (and elsewhere) for some suggestions of edge flow.
-try to keep polygons as evenly-spaced as possible. shouldn't have very big and very small faces (with a possible exception for creases, but that's it..). As long as loops have a good edge flow, keep polys more or less like a grid within that flow.
SYMMETRY. Insist on Symmetry. Asymmetry can be introduced with the rig afterwards, if necessary. But it can cause all sorts of issues with weighting and mirroring, and should only be used as absolute last resort.
Details
Clothing
a quick chain tutorial (Daniel Williams)
If you have clothing geometry next to skin geometry (ie., neck skin next to shirt skin), your skinning life will be much easier if the clothing geo mesh closely matches the skin geo mesh, both in density and line placement.
Face
Gorgeous Hobbit Face Rigs (thanks Jay Garrison & NY MUG)
http://vimeo.com/59582056 (pointpusher)
D. Pattenden's tutorial
Judd Simantov's reel
Brow - nice to have at least 5 lines here for nice creasing, raising, lowering.
Mouth Sock - should go all the way down and have a little bit of a throat, otherwise it won't look right when you open the jaw.
Foot
Cg cookie: http://www.vimeo.com/11483803
Hand
Cg cookie: http://www.vimeo.com/9742354
Hand Modeling Thread (archanex)
Make sure that you model the thumb in a lower horizontal plane than the fingers, even on a stylized hand. This will make it a lot easier to curl the thumb in to make a fist. It's also on a 45 degree angle from other fingers.
have enough geo around the finger knuckles to make realistic creasing.
Head
Cg cookie: http://www.vimeo.com/9059831
Olegon tutorial: http://olegon.org/..old%20files/human.html
Digital Animation Herts Uni UK Tutorial: http://lesterbanks.com/2011/04/creating-a-head-in-maya-complete-modeling-and-texturing-and-detailing/
Shoulder
Zeth Willie's modeling for better edgeflow: http://vimeo.com/57408254
Cg cookie: http://www.vimeo.com/10596662
Torso
Cg cookie: http://www.vimeo.com/13868566
Always put in at least 5 lines in crotch area (front), to be able to get good separation and movement between legs and pelvis area.
Wing
There is the question of whether to model feathers, or add them in procedurally?
Hind Leg
Make it far enough out from torso that it doesn't intersect abdominal area when moved forward or back
As with other areas, make edge loops as even as possible.
Modeling for Games
Is it better to break a game model up into several pieces for rigging, or keep as one piece?
You can have them all be one mesh or break it up. It's a matter of preference. (projectBrian)
Well, in theory, the objects that are not part of the body like the jetpack, etc.. would be either parented, constrained, or skinned to the skeleton of the body, again depending on your preference. That begin said you need to ask some questions like: Am I going to animate these parts for secondary or standalone animation off/outside the character itself? In that case you would want to give each of those parts controls for an animator to use. Then ask another question: Are these parts going to be deformed(i.e., squash and stretch or "pushing/smearing" the shapes)? In that case you would need to make joints or deformers for each object then give it controls and those controls would have parent groups that would be attached to controls on the body and then have attributes to allow for following the body controls or moving independent of the body. Does this make sense? It's a lot to think about for just starting to rig, but it's better to start that kind of thinking process now :D
(mattanimation)
Will the character ever remove the backpack or jets? If not it might be a good idea to keep everything together in one mesh.
Another skinCluster would require some extra memory to calculate.
(Emil Claeson)
Resources
Hippydrome's excellent site here
And just in! Hippydrome on Vimeo (thanks to Rigging Dojo)
General Modeling Techniques
Lofting and rebuilding curves to block out your mesh (Josh Robinson)