Fix and reset your Mixamo avatar rig
Creating avatars can be a delightful 3D modeling endeavor, but the technical side, especially rigging, often proves challenging.
The mission
Creating avatars is really fun, all that 3D modelling can be very fulfilling, I know. But after the fun part, comes the technical one, rigging.
On this post we'll explain how to use Mixamo to rig your characters in no time, and also solutions for some troubles you'll find along the way.
Resources
- Mixamo
- Maya
Rigging our character in Mixamo
Mixamo is an automatic rigging website tool that allows you to create quick humanoid for free.
Upload your character
Once you are logged in, press Upload Character and then drag the FBX you want to rig. Make sure to orient the model to have the front face looking forward!
Bone structure
After that, Mixamo will ask you to indicate different parts of the body on top of the model. You also can change the number of fingers you want in the skeleton by changing the Skeleton LOD.
Mixamo bone structure
For a VRChat avatar you want to use at least 3 Chain Fingers, because is the minimum that the game needs to detect correctly all the basic movement of your hand. If Mixamo doesn't detect 3 fingers it will create fewer chains, and you will have issues later.
Once everything is placed correctly, just click Next and the auto-rigger will do his work. If you are satisfied with the result, click Next again. Now you can see the character in different animations to ensure the quality of the rig.
Don't trust, test!
Before downloading your character from Mixamo, we strongly encourage you to run the following animations to test if there is going to be any problem with the avatar beforehand.
Some of these issues can be solved after downloading the rig, but others cannot!
Mixamo skinning test
Skinning test makes your character make really exaggerated poses. Perfect to see if there could be any skin problem beforehand.
Mixamo typing test
Typing is really useful if you want to check if your avatar has all the fingers rigged, since it moves all the fingers individually you can see if there are any issues.
Download that avatar!
If everything looks alright to you, go ahead and press Download and choose T-Pose and .fbx file.
Having trouble yet?
Mixamo's automatic skinning and rigging can work. But more often than not, your characters will encounter different problems that only can be fixed manually using a 3D software.
What went wrong? What do I do? These are questions that I made myself while working on these characters and I hope I can answer them here. Not all models are the same. Some have special characteristics and you have to look out for those.
These next examples will help you to identify and fix problems that could happen.
Bone influences
At first glance, this Hot Dog boy looks normal. It is in T-pose and it's completely rigged and skinned. Yet, there are some problems that we need to look out to.
Seriously, check what's given to you. Make sure everything is okay.
Mixamo places a shoulder bone between the Upper arm and the Spine_2 bone. This bone doesn't usually move around much, but Mixamo still puts influence, leaving some nasty results, like this one.
Lifting up 30º the right shoulder leaves us with an horrible looking deformation.
Mixamo shoulder bone deformation
This is the kind of stuff we should be aware of. For this particular case, removing all the influence of the shoulder bone will be enough to lead to some better results.
Removing all the influence sometimes is not the best idea so you can also reduce the amount of influence the shoulder makes on that part of the body for different results.
Look how the avatar gets to it’s original shape when removing the influences from the shoulder and arm.
Visemes issues
Blendshapes visemes gave us some problems when we did them with our workflow. Blendshapes in Maya use as a reference point the starting position of vertices BEFORE the binding process of the skeleton to the mesh (Bind Pose).
This is why, when we tried to make the blendshapes from the mesh we had exported from mixamo, we had this ugly result.
To fix this we'll reset our character rig.First, we will duplicate our original character.
Now bind the new mesh to the skeleton we have. Skin > Bind SkinSelect the old mesh, then the new one. Go to Skin > Copy Skin Weights.You can delete the old mesh, since it has no use. (Just make sure to test the new one before deleting anything).
Now you can start making blendshapes without problem!
Conclusion
Like any automatic tool, Mixamo is a great time saver that provides an easy way to go with decent results, but problems can arise, we covered some of the most annoying ones and hopefully this blog post helped you with your avatars.
