Clothing
Mechanical Rigging
skirts, coats, loose flaps etc.
Fk joint chains
Advantages - don't have to run simulation
Disadvantages - unless it's pretty far from the body, dealing w/intersections has to be hand done and tedious
non-realistic
Dynamic spline ik chains (using hair as the ik curve for the driven joint chain) attached to a the main root node.
Advantages - if you also add in a non-dynamic chain that you can switch between you can have a fair amount of control over the position of the cloth
Disadvantages - can be easy to see the different joint chains in the setup as they swing separately
have to run simulation
NCloth
Advantages - looks like cloth! Hence the name.
Disadvantages - have to run simulation
NCloth advanced techniques
http://images.autodesk.com/adsk/files/nclothadvancedtechniques.pdf
Modelling for NCloth
QUADS. Fairly evenly spaced is best.
fairly dense mesh (for simming) but not so dense that it will take forever.
Try to have it be one single layer--ie., no overlap at sleeves or anything like that.
If you model the clothes when the character is at its T-pose, it's likely that you'll encounter the problem you mentioned. Think about if you model the clothes when the character's arms are pointing downwards forming an angle less than 90 degrees with the torso. This would reduce the area of cloth under the armpit and thus would avoid the problem. This is a very superficial tailoring problem. Take a look at the proper character pose when I model the blouse in my blouse tutorial (http://sites.google.com/site/cgriders/jc/clothes/tutorial-blouse).
(fantasizer)
NCloth Attributes
NClothShape
What's the difference betw. painting texture maps of attrs and vertex maps??
from Maya help --Vertex Maps
Lets you paint any of the available properties on the component members of your nCloth constraints. The constraint property values you paint are stored per-vertex, per constrain component member. Select a property from the submenu: Strength, Glue Strength, or Weight.
Texture Maps--
Lets you paint any of the available properties on the component members of your nCloth constraints. The constraint property values you paint are stored to a texture file on disk. Select a property from the submenu: Strength, Glue Strength, or Weight.
But which is better??
texture map paints according to uvs, so it's faster if you have an object with the same uvs in multiple locations (ie., plant leaves..) Vertex maps allow to be more specific.
Either way, 'input mesh attract' weights don't seem to react differently unless value is set very close to 0, like .001 or .003..
Collide
use it.
Self Collide
uncheck unless it's really necessary, doubles, triples or more the compute time
Thickness
default is .010; setting it to something high (like .5) really increases compute time and also makes it bug out.
Trapped Check, Self Trapped Check, Push-Out
Pushout always works, even if trapped check is off and collisions are off. (one can actually use pushout instead of collisions) If a mesh has pushout then any vertices of other nObjects will be pushed along the normal if they are within the pushout radius. Pushout tends to get slower for large radius values. Pushout is along the normal, so it should be avoided if you want to collide both sides of a surface. When the pushout is 1.0 it exactly tries in one step to move the vertex out of interpenetration(including thickness values). (however in a single step other effects like stretch may tend to pull it back into collision... substeps will help with this) Note that values greater than 1.0 might result in an effect like an egg on a frypan.
The trapped check is like pushout, but it only works when collisions are on and just for triangles that are in collision. So if at the start frame you have two objects that are intersecting, trapped check will push out the vertices of intersecting faces. This is more efficient than pushout if one already has collisions ON, but it will not pushout triangles that are not interpenetrating. For example one could put a cloth sphere fully inside a cube and use pushout on the cube to push the sphere out of the interior of the cube. Trapped check could not do this. Trapped check is on by default for passive collision objects( which are assumed to be closed surfaces like a body ) while it is off by default for cloth objects, which tend to be two sided sheets.
Note that both pushout and trapped check are dealing with points being pushed out of a surface (like collision of an object with vertex collisions with a full surface collision object).
Note that there was a bug in earlier versions( I think it was fixed in 2008 ) where trapped check was computed even when collisions were off.
Self trapped check is not so much a pushout as disabling self collision where the surface interpenetrates. This keeps bad self collisions from getting stuck, but can in some cases make it easier to get more bad self collision. There is a little overhead to using it, and I would only enable it if you are getting some stuck self collisions. (you could even keyframe it if desired )
Self crossover check is less useful than self trapped check. It is a self pushout based on overlapping faces and it doesn't always push in the direction that will fix things(it does not use the normal). It can also add energy to the simulation in some instances. However you may find it useful for dealing with occasional self collision issues.
In general with self collisions the best thing is to have no self collision at the start frame and enough substeps for good collision behavior. If you have a very uniform and dense mesh then it often works best to use vertex self collisions with the self collide width scale set such the vertices just overlap.
(Duncan)
Also trapcheck and pushout only have an effect when the object collides with cloth or particles.
(Duncan)
Nucleus
Time Scale
Increasing it = big hit on performance
But it can help if you have a fast motion and cloth is not deforming properly.
Smaller time scale = more effect of gravity, noise, etc.
Space Scale
Very important to get right. Affects how much gravity, etc. affect the cloth nucleus.
Smaller space scale = more effect of gravity, noise, etc.
How to Calculate Space Scale
Simple tutorial by Todd Palamar: http://speffects.com/blog/2010/05/dancing-ncloth-cape/
Specific Challenges
Rigging Clothes to Take Them Off
Resources
40 Must See Cloth Sim Tips (3D world)