I have been looking more at the cat rig that James Waters originally rigged. Now that we are starting to do some animating with it there are some small bugs that are beginning to become a small problem.
This first video shows the problems with the rig. The ankle bends unnaturally so that the can cannot straighten it's foot. It always has a constant bend as the ankle joint is too high. The second problem which is shown in the video is that when the bottom is moved (like a sitting action), the underneath folds unnaturally and causes creases.
To resolve the ankle joint issue I had to remove the bound skin, remove the IK handles from the foot and move the joint to a better position. There seemed to be an extra, unnecessary joint in the middle of the forearm so I also removed that so it gave the cat a more natural skeleton. I had to re-add the IK handle once the joints were moved into place and parent it to the controller again. Before re-skinning the cat, I made sure the movement was looking better. I also repeated these actions on the other front leg. Finally, I re-skinned the cat.
I did not want to have to repaint all the weights for most of the cat so before unbinding the skin before moving the joint, I exported the weights of the cat. When it came to re-skinning, I imported the painted weights onto the cat and then only had to adjust the front legs.
Whilst repainting the weights for the front legs, I looked at the weights for the bottom joint to smooth out the creases. It took quite some time to sort out the creases because in the end, I removed all the influences from the vertices around that area and then re-added them by slowly building up the weight and constantly switching between joints to make sure the influences were then correct.
This second video shows how the rig responds now. The ankles have a more natural bend and creasing no longer occurs on the underneath of the cat.
No comments:
Post a Comment