Joint2Mesh beta2

Somewhere in RA someone mentioned something or other. Somebody else said something else. So I whipped out one of my old experiments.

This is something that I tried quite some ago when I first started my BVH project. Take the joint data, load up the mesh, and project the joint pivots to the mesh. I originally did this as a hack to see if I could customize the rig for animation purposes. Like markers in a motion capture deal. You know, wearhe marker textures, take some snaps, and use that to customize the rig.

So I hacked it up all over again. I did this real quick on the female mesh. One of the problems is that my scales aren't exactly proper. That is, I had to eyeball it. What little testing I just did on the main grid seems good for the elbows, but really kind of hard to tell for the torso joints that I did.

The thing that was mentioned in RA was about building armour and using the joint data as guides. However, I don't think that joint data like this will help much in this aspect. Why? Because the joint data doesn't really speak of the bone/envelope data. But it might help. I don't know for sure either way because I'm not sure how the enveloping works with the SL rig.

Anyways, give it a quick shot. Upload this and make shirt of it. Do some controlled experiments.

If anybody wants, I'm willing to toss up the joints as point helpers in a Max file. If I can find the one with the scale in the BVH files, I'll toss up that version. Maybe, just maybe, that version will fit nice and snug with the provided avatar OBJ files.

Cool thx will do

Hang on a tick...

Attached is another experiment I did some time ago. When I load the avatar OBJ files into Max, they are in chunks. These chunks are not by UV, but appear to be by major bone influence. I'm assuming this matches the the data found in the CR2 files sans blending.

Maybe, just maybe, this template will give a much better idea of how to prim an avatar.

edit:

One thing that might be interesting is to get the bone weights onto the mesh and into a texture. Chuck all of that into RGB for some pretty colours. Hip weight into R, abs weights into G, chest into B, and so on. Of course you will have to double-up on the channels, but that shouldn't be a problem.

Damn it. There I go again giving myself ideas.

Cool, the second one helped a lot, I got one arm done pre-decoration works, including a glove, just got to mirror it all tommorrow night then try the torso. Looking forward to fun on the stomach spine joints

I'm pretty sure that's the case. I wish there was some simple way to get the actual vertex weights, but I can't think of a way to do it other than taking screenshots wearing a template skin with poses designed for the task and fiddling with the weights until the skin deformations match. Thanks for posting these, Abu.

I've been doing a bit more poking around. The avatar OBJ that I have came bundled with the Poser CR2 files. Seeing how the CR2 files refference their respective OBJ files and name the chunks in the OBJs, I'm thinking it's a pretty safe bet.

I've also been looking into CR2 for the weighting information. It appears that they've taken a rather unconventional approach by defining envelope blends with angles. Which means that they are not exactly envelopes.

Check it out:
http://www.kuroyumes-developmentzone.com/poser/poserfilespec/joint.html

And in one of the CR2 files we find things like this:
angles 213.035 202.71 -18.5524 328.406

I don't know about you, but I really don't feel like translating all of those angles into weights. Ugh. And to make things even more interesting, the angles suggest ovals as oppossed to circles. Double ugh.

But all that is neither here nor there right about now for this thread.

If anything, the second texture that I posted should give the clothing makers a really good idea of major crease areas.

OK, I sense something useful here, but I'm too dense to understand what it is. Could someone explain what these two experiments are telling us, and how I can use the results? Sorry to be obtuse .....

Someone was asking if there were any avatar templates that show the joint locations of the avatars animation rig (it's skeleton, more or less). That would be useful for people trying to set up attachments, like armor, so that it moves gracefull with bending joints without coming apart or overlapping in an unattractive way. Vertex weights refer to the amount of influence a bone exerts over any given vertex, which controls how much the avatar mesh deforms in relation to the bones. For example a vertex in the middle of the thigh would be influenced only by the thigh bone. A vertex closer to the knee would be influenced by both the thigh and shin bones so that when the knee bends that vertex's position is influenced by the relative position of both bones. Knowing the vertex weights would be useful for replicating the avatar in an application outside of SL for animation testing, previewing texture stretch, and things like that.

Very cool, Chip. Thank you. So, there's a hint that the information may be useful as we're designing clothes. I'm not ever likely to be making armor -- although never is a very long time -- but if there's a way that this has a practical application in dressmaking, I'm all ears. It looks as if it might help define the problem areas for distortion a bit better, for example, so we can see exactly which cells on the UV map to avoid when placing detail. Yes?

Yep, correct, although you can already tell that fairly easily by making a skin out of my or Robin's templates and examining it on your avatar. Places where the grid looks especially blurry are due to polygons that don't receive enough pixels of texture to compensate for the amount they deform. Having joint locations and vertex weights on the templates would be mainly for working with attachments.

Yep despite trying a dozen varying skins, the multi colored jumper here is definately the best for trying to work out where the elbow joint is on a posed avatar, not perfect but a great guide it would be really cool if you could calculate exact coardinates from the avatars spine location, but then you'd have to allow for different shapes and poses animations too.
Yes more use when doing like I am trying to cover an avatar in unbulky armor head to toe. Try making prim gloves sometime!

Some of the earliest RL articulated gauntlets were actually "mittens"