Smooth weights causing spiky and odd weights

[Anonymous]

When smoothing weights seem to go to odd places and spike out despite joints that do not need influence being locked.

Link to screen recording of the issue: https://vimeo.com/manage/videos/542575837

[hamsterHamster]

The video link is empty.

You should be careful with Smooth tool in places where you have 1.0 (100% white) wights, as it will decrease the weight and the surplus is then split equally among the unlocked joints - then you are getting "spikes". Smooth carelessly when all joints but two are locked only.

To fix the skin you'd select the vertices of the spiky area and in Windows>General>ComponentEditor enter zeroes in the columns of joints that mustn't influence the area. When most removed, deselect and do SWPing again. You miight also use PruneSmallWeights command from Skin menu.

Also, consider Removing Unused Influences from the skin cluster, which can be found in the same menu.