View Full Version : Maya's CGMuscle + Sliding Issues - The verts 'pop'

07 July 2011, 07:57 AM
Hi everyone,

Just like the title says. We are trying to use cgmuscle to simulate skin sliding over bone, but there needs to be some form of a radius/falloff or something because currently the verts pop on and off the mesh they are sliding over. Shrink wrap doesn't help.

Only thing that does help even a little bit is the smoothing options in the cgmuscle system, but it destroys the mesh.

Cheers for any help!

07 July 2011, 02:15 PM
As I understand it, this is a common thing with muscle systems. Often studios still need to do corrective sculpting, or in some cases they simply use the muscle system to generate pose corrections for a smooth-skinned version of the mesh.
I don't have much experience with the plugin, though, so I can only guess at why the verts pop.

07 July 2011, 11:34 AM
With a 'standard' muscle system with independant skin sliding, the skin is searching for the underlying muscles, which are shifting position relative frame by frame.
From one frame to the next, the muscle may have suddenly disappeared relative to the search, (which could be using raycasting or proximity or whatever). This ON/ OFF approach can certainly produce popping from frame to frame

This test is of a muscle system I'm working on. It uses more than one search method, and if it cant find the muscle with one, it tries another and if that doesnt work, it just takes the average positions of its neighbours. The idea being that it eliminates popping.
Its done in Softimage ICE. Ignore the 'anatomy'. This is a technical test only.

07 July 2011, 07:01 PM
Hi guys,

The tutorial I was watching for this doesn't pop at all, only pops on my end - on my home comp, on school comps.

That's why I'm confused :(

07 July 2011, 08:06 AM
I still need help :(

Time's passing by and I still don't have a sliding effect in place... we need it for our movie.

07 July 2011, 04:43 PM
When in doubt, fake it.

07 July 2011, 08:18 PM
It uses more than one search method, and if it cant find the muscle with one, it tries another and if that doesnt work, it just takes the average positions of its neighbours. The idea being that it eliminates popping.

This is what SkinFX does too.
(Two rays to find the muscle, and a relax function to smooth out with the neighbours)

It works pretty well!

I like the sample video you showed. Looks like nice 'muscly' action :)

07 July 2011, 06:53 AM
Hi guys,

I'm in dire need of help now, the initial issue has been resolved - it was the relax feature. But now... my entire muscle system has been screwed up for NO REASON AT ALL. Everything functions perfectly except for the squashing and stretching of muscles. When it should be squashed, it squashes, when it should be stretched, it squashes, when it should be in X state (can occur at any point), it stretches randomly then springs back into another shape.

I know I'm setting the states correctly, the actual system is broken, and I can't afford to start all over and repaint all my sliding/relax weights again... there's quite a lot of them. And also, I'm not only rigging one creature, this has happened to me without remedy in the past and if it happens again, when the deadlines even closer, I'm royally screwed.

We're in production, got a million deadlines, shoot day's coming up, things need to be animated starting day one of the end of pre-production.

PS. This is a school project for the sake of education, we hire professionals in the areas that CG artists do not cover, I'm covering technical art and none of us have ever used CGMuscle before but we literally require it, we are doing an incredibly realistic project that will not hit the mark if it doesn't have a muscle system in place. Maya is our only option. As is cgmuscle at this point :(

And for those interested in what's being made, a lot of our school's movies get featured on cgtalk, so you'll all see the result of this project.

Thanks so much for any and all help.

07 July 2011, 08:37 AM
What about asking someone at Weta to help?
I guess you would have done that if it were an option. Is there no other Maya support you can ask?
What about finding another successful example that someone has made using Cmuscle and emailing them? It seems this feature is not widely discussed.

I like the sample video you showed. Looks like nice 'muscly' action :)


07 July 2011, 08:53 AM
Hi, their involvement doesn't span very far at all, I don't know how much I should actually be saying about the project. But I can't get help from them, they are letting us create something a concept artist there created for them, who is the person involved. I think I didn't word my thoughts properly - the team at weta have no involvement in it, and I don't know how to explain what I meant without disclosing too much.

Hope that makes more sense now :) or even less...

I will take your suggestion on board, and email some people. Cheers :)

But I'm still not closed to help on here!

07 July 2011, 02:22 PM
Sorry to keep repeating myself, but if the muscle deformer is such a problem, you really may have to look into alternatives. Especially on a short deadline, you have to determine which would be less time-consuming, and more stable - solving all the muscle problems, or transferring the muscle deformation to pose corrections (either blendshapes or PSD) on a smooth-skinned model.

Using pose corrections instead of muscles may not be the solution you're looking for, but it's at least an option to be considered. Plus it could be more educational, in a "think outside the box" way.

07 July 2011, 08:21 PM
The only alternative is to not have a muscle sim.

And that wont do, we need a realistic result.

Anyway, I restarted without simple muscles - because they break. Now I'm using muscle creator and the muscles influence the mesh in the wrong direction and there is no way to change it. I have tried every bloody setting (and there's a lot). I'm getting frustrated and no one seems to be able to help me with this.

It's like it thinks the muscle is outside, pushing the mesh forwards, it should consider the muscle inside, pushing the mesh back.

07 July 2011, 07:23 AM
Have you directly asked anyone who has used it yet
? I mean, it's very hard to find information on muscle but the chances is stumbling across someone in here is quite slim.
To be honest, I have never seen anything that impressive from it, but that
MAy be down to a lack of examples. But also, the muscles themselves seem way too simple in design to truly describe the complex forms thAt make up a body.
A muscle sim is great for certain stuff but a lot of the time you can fake it with comparible effectiveness. Maybe not to your eye, but you have to remember that you are keenly looking for the difference whereas most people will only be Interestedin what the character is doing.

07 July 2011, 07:39 AM
Tried, but not getting responses :/

I hear what you're saying about the believability of it... but eh, it's just an "extra touch". It's not 100% necessary, but we're all keen to have it in there and I really want to make it happen. If it doesn't work, we can drop it.

Oh and I forgot to mention! I fixed the problems, it appears the muscles actually have to be revolved to face -z if they are the back ones, and they're created +z.

CGTalk Moderation
07 July 2011, 07:39 AM
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.