Can I reshape the head then reimport it?

[Locola]

Hello,

I've exported an obj file of the basic human and extracted the head from it,
on the side I did a half face scan with photoscan and retopologized it using the makeHuman head
and R3DS Wrap.

If I were to saw back the modified head on the body model (obj) would it be possible
to re-import this model in make human (topology and uv are the same than the original model)
in order to work on the body?

Thanks.

[joepal]

You can re-attach it to the body outside MH (in whatever editor you want), and then produce a "target" using MakeTarget (in blender). This way you get a slider in MH for setting the head shape to your new head.

For MakeTarget, see https://www.youtube.com/watch?v=X13k7H3dNHo

A important issue here though: You MUST have the same number of vertices in the produced body, and the vertices MUST have the same order as the original makehuman basemesh. Otherwise, all the tools will fail. I guess it might be tricky to ensure that this is so in most editors.

[duststorm]

As Joel said, yes you can create a target from it, but you will have to make sure your base conditions are met:
- the mesh must have the same number of vertices as the mh basemesh (so you need to reattach the head back to the body)
- the mesh must have the same vertex order as the mh basemesh (wrap maintains vertex order, but of course if you cut part out of the mesh, when you reassemble it you need to take care that the vertex order is restored)
Luckily there is something such as Nuke Copy vertex by UV that you can use, with a bit of creativity, to restore your vertices in good order.
- the "ground" mesh, used to create the target on must be the same as what you plan to apply the target on. eg if you use the asian woman as base, and generate a face target for your custom face, when in MH you apply the target to an african male, it might not look like you had hoped. Do not make a target from the raw basemesh without macrotargets applied, because it does not look like anything you can produce with the makehuman software.
- mind positions: the makehuman basemesh is about 17 units high, has its hips on the world origin, is straight up and is looking towards you. If you move it around and create a target, you will encode all that movement in the target file, while you actually want your target to be minimal: only move the vertices of the face to form your custom face.

All of these are exactly the same considerations as should be taken when creating blendshapes. If you've ever done that before, most of this will not come as a surprise.

If this helps: wrap is designed so you can easily use it for creating blend shapes. You can import the entire MH basemesh in it, and then tell it to wrap only the face vertices. That way, you will not have to bother with reconstructing the mesh afterwards.
Make sure to align the scan to the MH basemesh during Wrap rigid alignment, not the other way around, so you do not move the basemesh from its original place.

To get a good basemesh to start from, I recommend the OBJ export from MakeHuman. Select "No eyes" from the Geometries > Eyes tab so that you have a mh basemesh with nothing added. Make sure to DISABLE "Feet on ground", because you want the hips to be at the origin.