PDA

View Full Version : Can bones share a weightmap?


Carm3D
09-29-2007, 09:08 PM
Hello,

I am considering purchasing XSI. I bought some training videos by Digital Tutors on rigging and overall I like what I see. But I am curious if it is possible in XSI to assign more than one bone to a weightmap?

Sbowling
09-30-2007, 05:26 AM
Hello,

I am considering purchasing XSI. I bought some training videos by Digital Tutors on rigging and overall I like what I see. But I am curious if it is possible in XSI to assign more than one bone to a weightmap?

Congratulations, you bought the worst possible rigging video on the face of the planet! :thumbsup: (I am required by law to say this every time this video tutorial is mentioned)

I'm not completely sure I understand what you mean with your question, because this is sort of the nature of bones. If you could have only one bone per weight map it wouldn't do much.

Did you mean something like more than one mesh/weight map per bone? For example, create different versions of a mesh (low res/high res) and have them all weighed to the same bones? If so yes.

If you meant something else, please explain. I can be very dense at times. :)

ThE_JacO
09-30-2007, 07:37 AM
xsi bones don't work the same way of LW or Maya, with one map for every bone, XSI uses an envelope map, which is a unified map used by the envelop (skinning) deformer.
The question can't really be answered, since the approach to envelope mapping is considerably different.

Carm3D
09-30-2007, 10:45 AM
Congratulations, you bought the worst possible rigging video on the face of the planet! :thumbsup: (I am required by law to say this every time this video tutorial is mentioned)

Oh poopie. Which video do you recommend?

I'm not completely sure I understand what you mean with your question, because this is sort of the nature of bones. If you could have only one bone per weight map it wouldn't do much.

Well that's good. In the video a unique weightmap (envelope) was created for each bone. I was thinking it would be a real pain if I created a series of muscle bones that go along a character's lips and I had to paint a unique map for each bone!

xsi bones don't work the same way of LW or Maya, with one map for every bone, XSI uses an envelope map, which is a unified map used by the envelop (skinning) deformer.
The question can't really be answered, since the approach to envelope mapping is considerably different.

Hmm... In the video, envelopes seemed to work the same way as weightmaps. Except for the nifty weight painting & smoothing tools. I figured it was just different nomenclature. Can you explain how envelopes differ from weightmaps?

BTW: In LW, I can use more than one bone for any particular weight map.

Thanks for the replies!

bravmm
09-30-2007, 11:10 AM
have a look at 3dtutorial.com and 3dquakers.com. Ecxellent tutorials and good value for money.

rob

pooby
09-30-2007, 11:17 AM
Hi Carm.

The difference is that LW's bones actually warp the space of the object. They are deformers that have falloff and will work even with no weightmaps, as their rest positions will describe a field of influence relative to the proximity of the vertices on the mesh.
Weightmaps in LW just limit each bone to a certain area. If the weightmap areas overlap then it acts as if there is no weightmap - ie the bones falloff dictates the influence.

In XSI the bones (or any other object you choose as part of your envelope but I'll just say bones from now on) do not on their own have any deforming abilites. So each vertex must be assigned it's association with the particular envelope bones that influence it.
This is done automatically when you pick the defomers and apply the envelope and at this stage it doesn't hurt to think of is as similar to LW's falloff.
However it is 'baked' onto the weightmapping of the envelope. It bascially creates weights per bone and puts these into one sort of compound weight (envelope) that contains all the information.
It's not the same as creating a regular weightmap.
When you paint the envelope, say, for example there is a vertex on the knee that is 50/50 distribution of influence between the thigh bone and the shin. IF you increase the amount on the thigh, it will take from the shin to keep the overall amount at 100%.
The Envelope is like a bunch of weightmaps that all work together to give an overall distribution of infuence.
LW's weights do not dynamically account for other weights in this way. They are like regular weightmaps in XSI, (which you cannot assign to bones (becuase as i said bones on their own are not deformers). but you CAN assign them to deformers (such as the push opertator) in XSI


I suggest just making a cylinder with an envelope of 2 bones and playing around until you go 'aaaaah i SEEEE'

Carm3D
09-30-2007, 11:46 AM
Pooby,

That's what I was afraid of. I noticed in the video when he adds the influence of one bone, it subtracts influence of other bones. I understand how that differs from LW weight maps. But I guess the answer to my question is.. No.. Only one envelope per bone / whatever. So if I have 12 muscle bones going along a character's upper lip, I need to paint weights for 12 bones. That sounds like a royal pain. Maybe I should look closer at Cinema4D.

Sil3
09-30-2007, 12:21 PM
You can tell XSi to automatically distribute the Weights on those new Bones when you add them to the Rig, but you need to fine tune them. Or simply dont let XSi assign them directly and do it yourself, I kinda prefer this method.

Remeber that XSis Weight System is Live, so you can immediat changes as you refine those.

Makes somes Poses on timeline with Keys and the change the Weights values, you can see their direct effect that way, so you can add or remove influence on thse deformers (the Bones) on the fly.

You can Paint(Add, Remove and Smooth) them or adjust them numerically for precise fine tunes(as I prefer).

At first and coming from a No Need to Paint Weights system as you are used it might sound like major effort, but it is not and soon you will find that theres a lot of strenght on this way, its not only drawbacks as you might first see it.

Plus dont forget that in XSi anything can act as a Deformer, give a look at Control Splines, yoiu might like those and incorporate them as Lip Deformers instead of only Muscle Bones.

Carm3D
09-30-2007, 12:27 PM
Control splines eh? Well that sounds promising.

Sil3
09-30-2007, 12:32 PM
Yeah they are powerfull, Messiah had something similar that I cant recall the name of it, basically just draw a Nurbs curve like you want, select it and on the left UI side on under Skeleton (cant recall the exact name not on my PC right now) choose Control Splines, choose the number of points you need on the PPG that opens and press ok, thats it :D

pooby
09-30-2007, 01:19 PM
So if I have 12 muscle bones going along a character's upper lip, I need to paint weights for 12 bones. That sounds like a royal pain.

Don't be put off.. I spent about 2 weeks complaining about the same thing when I came to XSI, boldly hailing LW as being more flexible in this area, but I'm eating my words now. XSI's system is far superior and easier to get great results. It just take a bit of a shift in workflow.
You don't have to paint each weight in the way you describe. For something like a lip where you want all the weights to overlap a lot, you just use the smoothing to get the influence right, then if you need to, subtract the influence from certain deformers on certain vertices.

Also The more 'bones' you have on a face, the less you need to fiddle about with the weights. I have a face rig with about 200 'bones' (nulls actually) and because of the dense distribution of the bones, the automatic assignment was very accurate and the only place I realy had to change the weights is around the lips, and even then, its not difficult to do.

Carm3D
09-30-2007, 01:32 PM
Thanks Poob, when I get more time I will get the 30 day demo and play with it

pooby
09-30-2007, 01:47 PM
The mod tool is good for learning xsi too, it doesnt expire and has pretty much everthing that's in essentials, including point oven. it's good to get if you don't think you're going to have a 30 day stretch at learning.
the main downside is that it has it's own scene file format, that you can't load into the full version.

Carm3D
09-30-2007, 01:51 PM
For some reason, I cannot install the mod tool. I tried. It said I do not have enough space in the specified install directory (61 GB free on the drive).

CGTalk Moderation
09-30-2007, 01:51 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.