I'm enveloping my character model and I'm trying to get the weights symmetrical. So I mapped the left side, then selected the vertices on the left side and went to Deform > Envelope > Mirror Weights, created my symmetry mapping template on the YZ plane, and pressed OK.

First of all, it doesn't really seem to do anything to the weights on the right side. Secondly, the left side's weights get really messed up and some of the mesh on that side gets distorted.

For the sake of experimentation I tried selecting the vertices on the right side and symmetrizing them over to the left side, and that had the same effect. The guide I followed was this one: Autodesk Softimage XSI Mirror weights

I just tested this in Mod Tool 7.5 on an imported character msh (all_inf_luke.msh) and it seems to work fine here.

Tagged some points
Animate > Deform > Envelope > Mirror Weights
Created default template
Deleted rule 9 and 10 -Validated
Intentionally messed up the weights on one side for testing
Tagged some points again on the foot and torso
Animate > Deform > Envelope > Mirror Weights
Everything worked as it should

By default my symmetry mapping template comes up with some pretty weird stuff (which I have tried to fix). This is a skeleton that I built from scratch (follows fred's bone names, hierarchies, etc).

Default symmetry mapping template: And here is what I've modified it to look like: Here's a screenshot of the affected area before I apply the weight symmetry (this is the side I'm copying from, the soldier's left side): And after the symmetry is applied: And as you can see the weights don't even map across to the right side:

I can't repro this. What happens if you use an existing skeleton instead of your custom one? Do you have any active operators (besides envelope op) on this character that might cause points to jump?

AceMastermind wrote:What happens if you use an existing skeleton instead of your custom one?

There's no point jumping, however I'm still seeing some very strange effects on the character's left (our right) - i.e. it looks like the right side's weights have crossed over partially in some places, but the same is not true in vice versa (the right side somehow remained unaffected). Screenshot:

AceMastermind wrote:Do you have any active operators (besides envelope op) on this character that might cause points to jump?

As far as I can tell, no. Here's a picture of my explorer window: Am I going about this completely wrong somehow? This is my first character model (ever) so my workflow has probably been the exact opposite of industry standard.
EDIT: It's worth noting that I have tried removing the Center operator but it makes no difference.
EDIT2: For the sake of experimentation I tried removing my weights and adding the envelope as a Modeling operator instead of as an Animation operator. I still get the really weird half-transfer from the right to the left side but no point jumping. Is this a step in the right direction? XSI suggests I keep the envelope under the Animation stack but perhaps this isn't the way to go here?

The construction mode you choose to place the operator shouldn't make a difference. I've never seen this happen before and I don't know what your workflow is like. If you have your character the way you want it I would clear the scene down to just geometry and freeze it, then bring in the unit template skeleton and start over, probably less time consuming than troubleshooting this.

Okay. I'll probably go ahead and do that. Thanks for looking into it anyway.