Keep Daz Rig when converting seems to mess up feet

[Poppedri]

Using Blender 3.6

Diffeomorphic 1.7.2.1892

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When converting rig to MHX or Rigify while enabling “Keep Daz Rig”, the feet seem to get some really bad inaccuracies. The feet are a lot worse in MHX compared to Rigify, but problem exists in both. Converting normally without Keep Daz Rig works fine. Here is a comparison image from behind the heel:

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[Thomas Larsson]

Hm. Unfortunately, this looks like a design flaw rather than a bug.

The mhx rig is based on the original daz rig, but some changes are made to make it better suited for posing in Blender. In particular, the foot and tarsal bones are moved so the toe bone is connected to them. This is crucial for making the reverse ik foot work properly. Changing the location of the bone tails in edit mode does not move the mesh very much, and nothing at all in rest pose. However, if we keep the daz rig, the daz bones have copy transforms constraints to the corresponding bones in the mhx rig, and since the rest poses differ, the daz bones are aligned with the mhx rig. That deforms the mesh.

The picture below shows how the mhx and daz bones differ in rest pose.

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[Poppedri]

Is there no good way to keep the rest pose for both rigs matching?

[Thomas Larsson]

In the last commit I implemented an option to modifiy the rest pose of the deform rig to match the control rig. This will cause inaccuracy if you save a pose preset, but perhaps that is a lesser problem.

[Alessandro Padovani]

For connected bones you could copy in local space rather than pose space, this should keep the offset and match the pose. In particular in this case copy in local space for shin.

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[Thomas Larsson]

No, I think we tried that before, and it led to foot sliding.

[Alessandro Padovani]

Foot sliding is not possible by definition if you use pose space for the foot (aka the ik targets). Then the daz rig must be unlocked in daz studio for the ik pose to transfer correctly as usual. I believe you’re confusing copying all in local space that’s not good.

That said I don’t use mhx myself so please verify. I do it in my rigs and it works fine for me.

[Thomas Larsson]

Yes, I can verify. With all copy transforms constraints using local space, the deform feet slide when I move the hip bone.

[Alessandro Padovani]

Again, local space for all is not good. Please use it only for shin and leave others in pose space.

update. Ok, just tested and works fine here. There’s no foot sliding in blender or daz studio.

steps:

1. change shin to local space
2. animate
3. select the daz rig and unmute
4. save pose preset
5. in daz studio unlock and import

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[Thomas Larsson]

OK, I changed the shin constraint to local space. The foot moves slightly from rest pose, if that is a problem we can still enable the Modify DAZ Rig option. If enabled local or pose space shouldn’t matter.

[Poppedri]

Thank you, that works a lot better.

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