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View Full Version : Weight Map Workflow/Vertex Paint and SubPatches?



Giacomo99
05-23-2007, 04:20 PM
Hello-

I'm doing some fairly precise character work for the first time and I need to be able to fine-tune bones and weight maps.

I started by using skelegons and converting them in Layout, but the problem is that Lightwave is just too unstable for this to work: If I make minor adjustments to skelegons in Modeler and try to update them across the Hub, Layout either doesn't recognize the change or it just crashes. I tried deleting the model from Layout, saving an incremental version in Modeler, and sending it to Layout again, but Layout <i>still</i> gets confused and doesn't recognize the updated version. The only possible workaround I can think of is to shut down the Hub and save each increment under a new name. This seems excessive.

So I tried Vertex Paint, but Vertex Paint doesn't seem to work with SubPatched objects.

I need a way to make small, precise adjustments to bones and weight maps with real-time feedback. Is this possible in Lightwave? Please advise.

SplineGod
05-23-2007, 06:45 PM
What is it that youre doing? This may help in giving some useful advice :)

Giacomo99
05-23-2007, 09:17 PM
http://home.earthlink.net/~bucket/CubeGuy.jpg

This is a simple character (for clarity, only half of it is shown here)--basically a cube with arms (only two joints per finger), all FK. It's intended for a high-res print image, so the important thing here is that the hands need to look good when posed--no weird deformations.

Right now the weight maps are: the entire arm, the forearm, the hand, and one for each finger--100% strength for the relevant area, dropping to 75% for the set of points immediately adjacent (hope that makes sense.) I can post screen caps, but I don't think it's necessary.

The cap I posted is partially posed (I modeled it with the arms straight out.) It occurs to me as I write this that I might have an easier time of it if I pre-bent the joints a little more.

It also occurred to me that I could freeze the mesh and try to use Vertex Paint, but this is a print job, so the model needs to be smooth. I tried to compromise and freeze the mesh at a subdivision level of 2 (with the intent of SubPatching the frozen mesh), but that turned out to slow things down to the point of unworkability.

But the larger problem is that I don't really know where to place the bones in the hand with regard to the weight maps. If I use no weights at all, the fingers just look terrible when bent (the main hand bone and the finger bones do not seem to get along), but I can't seem to get the maps right, either. What's in the image above is sort of a half-assed attempt to keep the main hand bone from exerting too much influence on the fingers by keeping it short and extending the finger bones into the hand (which I suppose has the virtue of being anatomically correct, sort of.)

So there you have it. I'd really love to be able to tweak the maps and the bones interactively, if for no other reason than to get a feel for how the system works. Right now the only stable workflow I've found for adjusting the maps is to save each revision out of Modeler, reimport it into Layout, convert the Skelegons and test the joints--which is tedious and slow.

Sensei
05-23-2007, 09:30 PM
ShowWeights http://www.trueart.pl/?URIType=Directory&URI=Products/Plug-Ins/ShowWeights
allow you to see values of weight map during you modify them by any tool, all the time. Basically you use Weights interactive tool, and have Show Weights enabled and each vertex can be precisely adjusted.

SplineGod
05-23-2007, 10:03 PM
What is your bone falloff set to? I can typically setup hands and such like that without weight maps and get good deformations. Instead of weight maps Ill add hold bones here and there to help keep the shape or improve deformations.

Dodgy
05-24-2007, 03:16 AM
For the hands, turn on Joint Compensation and Parent Joint compensation and the Muscle flexing options and you should see your fingers deforming better, if you have enough polys. For such a simple object, you'd only need two weight maps, an arm weight map and a cube weight map (if at all). Then assign your bones to one of the two maps to limit their influence to that section.

Giacomo99
05-24-2007, 02:26 PM
http://home.earthlink.net/~bucket/CubeGuy24May.jpg

It's working much better now--thanks very much for the help. About 95% of the problem was solved by pre-bending the joints in Modeler. I ended up using only two weightmaps--one for each arm, thanks Dodgy--and they seem to be working OK. The only thing that remains is to soften the weight map's dropoff where the arm joins with the cube. (Hopefully if I do this in Modeler, Layout will recognize it without having to reimport the model and start from scratch.)

As so often happens, this has raised in my mind about a million questions more than it solved. Hopefully you guys will be around to help me out as I push forward into more complex territory.