Methods for aligning high res sculpt to low res mesh?

7089tPp

Wondering how people have successfully aligned a high res sculpted mesh (e.g. Sub Division 5+ in Mudbox) to a low res mesh with different vert IDs and topology than the Sub Division 0 base mesh in Mudbox.

In Mudbox we've experimented with setting the Sub Division level to 0 for a sculpted mesh and then importing the low-res re-topologized mesh into Mudbox using Import Layer > UV Position (the UVs of the sculpt and the low res mesh are aligned). Sometimes it works and Sub Division 0 morphs to align with the imported low res mesh. But most of the time it gives an error saying something like "Imported mesh is not a Quadric Mesh" and the import fails. Any ideas on how to make Import Layer > UV Position actually work? I guess you aren't technically aligning a high-res to low-res, since it's set to Sub Div 0...

For some meshes, we were able to eliminate this error by taking the low res mesh into Maya and dividing it using Edit Mesh > Add Divisions > Quads. However, inevitably Mudbox gives the Quadric Mesh error again even with this divided mesh.

yiannisk

By saying UVs are aligned you mean they are identical?

Usually what i do is export the displacement map from the sculpt, then subdivide the mesh (which has the same UV mapping though) and apply displacement on an equally subdivided mesh.

In some cases depending on the model\use i do not even make a retopologized mesh but use the lowest level of mudbox. Since that exactly fits and that was the model my normal maps were generated on.

I have not tried the workflow you mention.

7089tPp

By UVs aligned I mean the UVs are laid out on the base mesh that is going to be sculpted. Then after sculpting this base mesh is retopologized but the UVs are untouched. So it's a different number and translation of verts, but the UV shells are roughly aligned.

I've resorted to exporting the Sub Div 0 into Maya as an FBX where my retopped mesh is and then doing a Mesh > Transfer Attributes > Vertex Position On, Sample Space UV. I then export the aligned Sub Div 0 as an FBX out of Maya and Import as Layer > Vertex ID into Mudbox with the sculpt set to Sub Div 0. This allows the rough shape of the ReTop mesh to morph the sculpt. I then PageUp the divisions to 5, Import my ReTop FBX (which has different topology from the Sculpt Sub Div 0). Now I have my Sculpt overlaid and aligned with my ReTop and I can do a nice Normal Map Extraction onto the ReTop for use in-game.

This works well for aligning the Sub Div 0 to the ReTopped mesh because they have roughly the same number of verts. However, if I were to bring in Sub Div 5 to Maya and do Transfer Attributes, the Sub Div 5 wouldn't smoothly interpolate its alignment with the ReTop mesh, it would actually morph into a blocky shape (picture the high res mesh shrink-wrapped to the low res). While I doubt there would be many cases where I'd need to morph a high res mesh to a low res, I'm still interested in finding a solution for that edge case..

ralusek

i'm not exactly sure what you're trying to do. are you talking about creating normal maps? what exactly are you having problems aligning, the position and scale? because if you retopologize you should have no problems on this front, but if you're creating a completely new mesh from scratch then you'd have to make adjustments.

again, not sure if this is what you're asking, but to actually transfer detail in zbrush (don't know mudbox) you simply append the sculpted mesh to the retopoed one, divide the retopo, and project.

if you clarify what you're trying to do exactly, i'll try to help you more

edit: because to create a normal map using xnormal, the high poly doesn't even need to be uv mapped, and definitely doesn't matter if the uv coords differ from the low poly

pior

Yeah, no idea what you're trying to do here!
Simply post a picture of what you're working with. It seems like you are over complicated the problem tenfold.