Transfer skin weights from a simple to a complex model

mike85

Hey everyone,

I need to transfer skin weights from a really simple to a more complex non-organic model (car body).

I am making a mod for Automation car tycoon game and a deformable body ("morphs" for bumper, roof shape, wheel archs etc) is required for a player to be able to change the car shape.

The body itself has a pretty complex and dense topology and I don't see how it could be skinned with standart 3ds max tools (see pic).

My first idea was to create a simplier topology and add skinning to it:

Then copy the skin with Skin Wrap tool, usually that worked for me with characters.

Unfortunately, when I use Skin Wrap, it is a total mess no matter what settings I use. Could anybody please give me some advice? Thanks.

oglu

Are you using maya? 

pasha_sevez

Your idea is actually good. Unfortunately, it unlikely can be solved with out-of-the-box tools (not in Max or Maya, at least). Because it requires some advanced interpolation methods like RBF, biharmonic coordinates, mean-value coordinates and so on. As you can see, the standard shrink wrap is not a way to go. Many studios have a lot of in-house tools of this kind, but they never put it into public access.

pasha_sevez

But you can try to drive a tessellated version of your cage with a low-poly version. And shrinkwrap to tessellated version instead. Probably this may help.

mike85

pasha_sevez said:

But you can try to drive a tessellated version of your cage with a low-poly version. And shrinkwrap to tessellated version instead. Probably this may help.

At least in 3DS Max it is not possible to use skinwrap if there is a modifier on top of skin of the source mesh. Is that the same in Maya?

oglu said:

Are you using maya? 

Nope, 3DS Max, but I can switch to Maya LT if it can provide me better tools for the task

pasha_sevez

mike85 said:

At least in 3DS Max it is not possible to use skinwrap if there is a modifier on top of skin of the source mesh. Is that the same in Maya?

In Maya it is possible, but the result leaves much to be desired and introduces the typical interpolation artifacts.

coven

Skinwrap doesn't care what is on the source mesh. All it is doing is is wrapping by closest point, and gives you control over the falloff. You could skin your mesh, then add a tesselate modifier to it (using face and setting tension to 0.0). 

You will still have some warping, but if you increase the tesselation, the skinwrap will have more information in what to follow, so it should help alleviate some of the warping.

poopipe

I've done things like this many times - usually for  character customisation and facial animation.
Basically just do what coven says. 

I usually found it safest to drive the actual deformation with blended morph targets rather than freeform movement  because that allows you to control the extents of deformation.