Wrist twist collapse in editor

Hi All,

So a weird thing is happening in UE4 with my mesh. Inside of Maya the wrist appears fine when twisted. But in UE4 it appears to have collapsed in on itself. I have included a comparison image of the same mesh at the same frame, for reference.

If anyone can provide insight on the matter it would be greatly appreciated.


Same here, in my case the player character has same issue with you but the enemy characters. They skined same way in 3ds max by the way… any progress KyFer?

Candy wrapper artifacts are neither wierd nor should they happen at all.

Hold your forearm on a table and attempt to rotate the hand the same way you are asking the engine to rotate it.

This is due to the fact that you don’t have any twist joint in your character lowerarm, so when you rotate the character, the lowerarm won’t rotate at all, causing the candy wrapper issue.
If you check either the Mannequin or a Meathuman, you’ll notice that you have 2 twist joints on the lowerarm, and the skinning on the lowerarmis kind of divided into 3 sections:
Twist joint lowerarm1: close to the wrist
Twist joint lowerarm2: middle of the lowerarm
lowerarm joint: close to the elbow

You do need to “link” the rotation of the twist joints to the the wrist, and in order to do so take a look at the Metahuman Post Process AnimBP, there you’ll find how to create the rotation link between them…the setup is for the control rig, but you can apply the same logic in AnimBP.

You are simply asking the engine to perform a motion that is anatomically impossible.

The original mannequin does not have a twist on the wrist. Nor is one required.

The weight paint is distributed so that the rotation and candy wrap effect occur where they should. At the middle of the forearm.

You can also think of it as rotatating the elbow rather than the hand itself.
The correct pose, in the end, will likely be a combination of both bones rotating. Just like your forearm actually works.

Assuming you have decent weight paint at least. If you mikymouse stuff, then there really isn’t much hope of the rotation not looking mikymoused anyway…

Download/get a Genesis 8 and study how that is done.
I doubt metahumans have anytning even worth consideration.

Genesis 8 model character is a good example for CG character, terrible for game characters, due to the fact that the arms and leg joints are chains, opposite to the Metahuman/Mannequin character, where the twist joints are attached to the main joint ( lowerarm twist joints are children of the lowerarm, upperarm twist joints are children on the upperarm, and so on ).
The only way I managed to get IK working with Genesis8 characters is by using virtual joints, so imagine doing this for every single character…and the twist joint setup is very annoying due to be a chain.

So long story short, Metahuman characters do have a twist joint setup, but as of now gimbal lock is still an issue ( I solved this via BP ), and the team is planning to upgrade the setup by avoiding gimbal lock with Control Rig.

Where bones are physically should not really matter. Never has before, don’t see why it should now…
Sure, it’s not the best bone structure, but it’s designed to work the automated corrective system…