Hips shift forward with VRIK 1.9 on some models

Question

This issue is basically the one described in this previous post. The model in that post seems to be a VRoid made model. I have encountered the same issue on version 1.9 of Final IK with my own VRoid models. A non-VRoid model I tried worked fine however. A simple example scene and model illustrating this issue can be found in this unitypackage.

Any help would be highly appreciated. Thank you!

Answer 1

Hey,

It usually happens with some models that have the spine bone too close to the pelvis bone. So any changes applied by VRIK to the spine might result in violent pelvis rotation. Please try using the next bone for the Spine in the References if possible.

Best,

Pärtel

Comments

Thank you so much!

Using the chest in place of the spine bone and leaving the chest empty helps. In the end, I just moved the hips bone downwards in Blender to avoid the issue entirely. I wouldn't ever have thought of trying that without your advice!

Edit: After investigating some more, the strange hip bone position was caused by using the Blender CATS plugin's "fix model" function to clean things up after importing it from VRM. This has been fixed in version 0.16.1 of the plugin and it shouldn't happen at all when importing the VRM file directly into Unity.