Blender Rigging and Animation

[Neutronux]

@ODN_Wesley;672223

Makehuman -> Blender -> UE4. That would be:

*) In Blender ensure your Frame Rate is set to 30, Scene units set to Metric, with Unit Scale 0.01.
*) Export from Makehuman as Collada (dae) format and Scale Units set to “centimeter”.
*) Import into Blender
*) Import the UE4 mannequin into Blender (This is your exported UE4 SK Mannequin that has been exported as FBX from Unreal Engine).
*) Put your camera in Front Ortho view. Resize the UE4 mannequin mesh with your Pivot Point tool set to 3D Cursor and then by pressing “S”.
*) Pose the Makehuman character to get a (very) similar pose to the UE4 mannequin. To do this: In Pose Mode select the individual bone joints and move them using the arrows so that they closely match the layout of the UE4 Mannequin. (afterwards delete the UE4 mannequin)
*) Apply the armature modifier to all of your meshes. To do this click on your character in the Outliner. Expand down, and beside each of your Meshes click the wrench icon. Then click “Apply”.
*) Apply the pose as new rest pose in pose mode to the skeleton. Select your character and choose “Pose Mode”. On the bottom left Blender menu click “Pose” -> “Apply” -> “Apply Pose as Rest Pose”
*) Add armature modifiers back to the meshes. To do this select your character in the Outliner. Expand to your meshes. Click the wrench icon. Click “Add Modifier” and select “Armature”. Set the Object as your characters Armature. (Don’t click Apply).
*) Add twist bones (they are a must have). Copy vertex groups (e.g. upperarm_l) and split the weight up (autonormalizing on and subtract and blur) between the twist and the normal bone. (Not sure the exact steps on this but needs further documentation).
*) If you like you could add some IK bones. They are pretty useless in UE4 (as you could use the IK functions even without them in UE4) but very handy while animating in Blender. (Should add documentation for this too for animating in Blender).

Looks good :). Regarding that twist bones. Take a look where they are on the UE4 mannequin. Think of it like you split up the weight of one bone to two bones. But the bone itself is not split. They are more parallel. The twist bone is a child bone (if you move upperarm_l then upperarm_twist_01_l should follow). If you have an animation without any critical pose than there should be no difference between a mesh with or without a twistbone.

Some example:

Starting point - weight of lowerarm_l vertex group (and a pose that looks bad without twistbone):

Add a bone (use shift-s and snap curser and start/end point of the new bone to get good start and end points based on the already existing bone). Even take a look at the mannequin which bone is a child of which other bone and afterwards copy the vertex group:

This causes too much weight. You’ve got 1.0 on some vertex at lowerarm_l and 1.0 lowerarm_twist_01_l now (= 2.0). Make it that it’s either 1.0 lowerarm_l and 0.0 lowerarm_twist_01_l or 0.5 lowerarm_l and 0.5 lowerarm_twist_01_l (subtract/blur with auto normalize):

Result is split up weights:

…this one is already rotated as you can see the result (the pose is still the same … the only change is that the weight that was on one bone before is now split up on two bones and the twist bone was rotated parallel to the lowerarm_l bone):

But as you can see if I select both bones… it’s still the known weight that you had already previously. So you don’t have to think a lot where the weighting starts or ends at the ellbow for example. You just remove the weight at one end for the first bone and the weight on the other end for the second bone (you have to take a look a bit how it looks good so a bad pose is a good starting point… and even keep the wrist in mind). At the upperarm_twist it’s not the lower part that is critical (wrist) but the upper part (shoulder)… and so on.