View Full Version : Multi-objects or single mesh

01 January 2003, 02:55 AM
Hi all,

I have been wondering what the big studios do when it comes to rigging and skinning a high-end character for film, when there are many parts to a single character.

Specifically, when and why do you leave a character as many objects, like body, clothes, a belt, etc or have them as all one object with each as a seperate element.

Now putting flowing clothes aside, as they would be a seperate object with a cloth simulator, hence no rigging or skinning. What about the rest?

Starting with the head, I am assuming that the eyes and tongue would be seperate objects, but what about the teeth/gums. Figure that this is not for a dentist and you will not be pulling the lips completely down and seeing the base of the gum join the mouth. Do you make the teeth as part of the head or leave them as a seperate object. Either way what effect does this have on skinning and later general animation both lip-sync and facial expressions.

Another area is with tight fitting clothes, now one could attach them to the body, hence only one object to skin. If you do, what about the model under the cloths, if you delete the poly's, how much do you remove. Lets say that the clothing cross's midway over a body polygon, if you delete all of the polys that are completely under the cloths, is it possible that it may stick through depending on the skinning and given its sudden stop.

The other option is to not just attach, but weld the clothing or any other item that covers part of the body so that it is really just one mesh. I guess this is just like a 3D game model but do you do the same for something like the characters in Shrek or a CGI Orc in LOTR.

While that would stop any under model poking through, it would also mean that both body and clothes would be skinned the same and move the same amount. Now I guess for very very tight things this would be true, but for anything else, some slipage would happen and so the clothes would have to deform a bit different. Or is it just a case that all clothing is done as a cloth sim, even something like the top half of Fiona in Shrek?

So what do you do and more importantly what effect does the choice have on skinning and then animation?

Jason, how does Weta handle it?


01 January 2003, 10:11 AM
In head, eyes will be parented to the head joint instead of skinning it( and only when required it should be skinned)
maximum gums will also be parentend and whild doing facials , according to the facials gums will be placed and use it through blend shapes, instead of making teeth as part of the head,

i dont delete the polys, under the cloth, instead while weighting, hide the cloth and weight the polys first, then hide the poly and weight the cloth next,
important thing is if the character is for game, its better to have single mesh instead of polys under cloth, modell in a single mesh, apart from game, it good to skin everything
this is how i do in my studio

01 January 2003, 10:35 AM
Hay dynafx, thanks for the info. Any real reason for having the teeth seperate?

As for leaving the polys, don't that make the model more heavy then it needs to be. I know for games it needs to be one mesh, but I guess keeping them seperate does have the advantage that you can partly weight the clothes different from the body, as long as the body doesn't poke through, it allows you to have a more cloth movement and feel to the clothing, is that the main reason for doing it?

01 January 2003, 08:45 AM
hi there, interesting thread ...

I'd like to ask about the head when using morph facial anim.

For a naked character, do you guys use morph target/blend shapes of the entire body ? or is there a way to cut the head without seeing this cut in rendering ?

01 January 2003, 09:04 AM
hay CiF, yeah the thread would be a bit more interesting if a few more "pro's" would reply, still maybe they will in time.

As for the facial morph, I don't know about other packages, since I only use max, but with max, yes you can keep the head "seperate" but not have a seam. The stack would look like this:

edit mesh <- this is used to attach the body to the head and weld vertices
editable mesh <- this is just the head mesh

I assume the other pakages can do much the same thing, unless max is just that much better :)

01 January 2003, 09:14 AM
thanks a lot tony !!!

even if not so many people answer your questions,
at least you answer mine .. thanks :buttrock:

actually the answer is pretty obvious .. I'm so dumb sometime :hmm:

thanks for opening my eyes :surprised


01 January 2003, 09:35 AM
np, I remember reading it myself on a forum sometime ago, yeah pretty obvious, once you hear it :)

01 January 2003, 04:32 PM
In Maya, i had the body as one mesh, and used a wrap deformer connecting just the head to to whole body (believe i set the weighting to 1), so i only had to make blend shapes for the head and there was no seams on the body in the animation.

02 February 2003, 04:50 AM
So, anyone else want to take a crack at the first question, where are the "pros" when you want them :shrug:

Iain McFadzen
02 February 2003, 09:22 AM
There's no "best" way to do anything, you'd probably build and rig your character by whatever means were fastest and most straight-forward.

Doesn't matter whether the character is one object or hundreds since you can include multiple objects in a single Skin modifier. If it's easier to model them separately or there is an obvious reason to do so (eyes etc) then model 'em separately.

Eyes, toungue, teeth would probably be separate, and linked to the skull.

If the character is wearing clothes then you wouldn't model the body in the first place (no point in modelling something no-one will ever see), unless you knew for a fact that the body will seen at a later date. Even then you'd probably use two different models. If you need to simlulate cloth you'd use a really low-poly non-renderable mesh as a deformer. Tight clothes can just be skinned along with everything else.

Like I say, it doesn't really matter how you choose to go about it, all that matters is how it looks in the renders, so you just do whatever is fastest/most reliable/easiest etc.

02 February 2003, 03:10 AM
Cool, thanks for that Iain, I guess in the end I was wondering if there was one really down side to doing something one way and not other. I suppose in the end it really can depend on the character and knowing what works only comes with experiance.

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