CGTalk - Rigging a towel

StefanAlbertz

08-04-2009, 10:15 AM

For an upcoming project we need to animate a towel. In the shot it´s formed to a ball and the 3d part is, to unfold/unwrap it into its normal form.

First test i did was creating a quite high-res towel then creating a spline-like skeleton (the "spine" running through the middle of the long side of the towel, "ribs" coming out from each spine-joint to the outer side of the towel). Now, when rotating the spine-joints to wrap up the towel, between the bones the deformation is somehow crumpled. I guess the joints-influences disturb each other.

any idea how i could do a better rig for this occasion? The towel should be able to bend about 2 times (rolling up about full turns).

Boucha

08-05-2009, 01:12 AM

I think you can work around this using a combination of indirect binding and inbetween blendshapes. Indirect binding means using a lattice to deform the towel geometry. The lattice will be the binded to joint and settup you desire. Using inbetween blendshape for rolling and folding will be much predictable and accurate and can be easily layered upon existing deformers.

uiron

08-05-2009, 08:31 AM

joint-based deformation won't work here. just try stacking bend deformers; your towel geometry should be pretty dense. i once animated a paper-fold plane, which had many more than two folds - simply simulate bending by placing bends where they need to be.

StefanAlbertz

08-11-2009, 03:15 PM

Thanks for your input! It worked out with a combination of bends + joints + wraps + blendshapes.

The spread-out baseMesh (laying flat on ground as later controller for the real-object) got 2 bend deformers, slightly tilted so that they were able to wrap up each side. In the middle along the long side of the towel i created a skeleton (joint number = number of vertices in that direction). Binded it, put a spline ik into it, created the knot with the curve (inserting new cvs into the curve where i needed them). Then, i created clusters for the first 4 CVs and keyframed them on frame 1 - on frame 0 i stretched them back on the floor so that in frame 0 the baseMesh layed flat on floor, on frame 1 the knot is build.
With this, i attached the real object to the baseMesh using a wrap deformer - done.

Blend shapes are currently build using zBrush to sculpt more detail into the towel.
Nice add-on: even nCloth is applyable on the baseMesh and works even with the splineIK.

Thanks again for input!

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