hiRes/loRes Model Skin Weight Transfer

[jullman]

Hello,

I am working on a character which has hiRes and loRes versions bound to the same skeleton. This is so I can hide the hiRes during animation to increase performance, yet only render the hiRes version. My question is, I am currently painting the skin weights for each joint on the loRes version. Is there a way for me to transfer these weights to the hiRes version? It is not out of the question for me to make a new version of the hiRes version by duplicating the loRes, smoothing and binding to shared skeleton. Is there any way to do this?

Thanks,
Jeff

[badcookie]

Just some thoughts...

you are using polygons, you can just weight the low res, animate it, and then with history on, smooth it before render. if you need to tweak the anim, you can always go into the smoothing history node and set the divisions to zero again to get a low res.

[goggle]

If you are indeed using polygons then the possibility also exists of using your loRes model as a wrap deformer for you hiRes model. That way your bones deform your loRes and your loRes deforms your hiRes. Although some people seem to run into problems with system sluggishness with this method.

Hope this helps.

-James

[warpcat]

While you can copy the smooth weights of the low-res surface to the high-res surface, it will give sub-par results. Maya won't interpolate any additional weights,.... meaning if there are say, 10 high-res subidivsions between two low-res ones, the high res subdivisions will simply inherite the closest weight, without generating a nice falloff. If you weight the high-res first, you can copy those weights to the low-res no problem though, because there will be an overabundence of data. I would go with one of the previous two posts. It's possible, although I havn't tried it, that if you save out the weight maps of the low-res surface, you may be able to read them back onto the high-res surface, presuming they were uv mapped the same.

[jullman]

Thanks for your help, I will try these out.

Jeff

[joojaa]

Warpcat... m not entirely sure but doesent the wights get iterpretted as image files (if not you could convert the data to such)?

If so then just resize the array in PS or something with bicubic sampling...

[warpcat]

right, if you export the weight maps they do. You don't even need to resize them, but your target geo needs to be UV mapped the same as your original geo, so it can get trickey. However, if you simply preform a "copy skin weights" function, Maya works some internal magic by projecting weights along vertex normals and what-not (by my guess), to transfer the weights from one surface to the next. And because of that, it won't interoplate any "new" or "inbetween" weight values.

[skullnation]

Your best bet would to be to cut up your lo poly model and into a piece that will correspond with each joint. So basically you would say, select the faces at the elbow and delete them then go to edit polygons>separate now you'll have to separate polys and you can parent the forearm to the forearm joint and the upper arm to the upper arm joint and the shoulder to it's joint and so on. This takes a relatively short amount of time and parenting will give you much better real time performance then weighting it ever will. Now you can spend the rest of your time focusing on weighting your hi-res model and getting the deformations correct.

This also works with NURBS models by just making a copy of the pieces and detaching them at the joints and such. Anyway, hope this helps.

Cheers!