Friday, September 11, 2020

HD Meshes and Geografts

Update September 18, 2020. 

engetudouiti found a way to export the individual HD meshes so that lower subdivision levels can be built, even in the presence of geografts.



In the previous post we showed how a HD mesh from DAZ Studio becomes a mesh with a multires modifier in Blender. This works because the Rebuild Subdivisions tool converts the imported HD mesh. However, for this to work the HD mesh must be a clean subdivision of the base mesh. If the HD mesh has geografts, typically genitals, it is no longer a clean subdivision and rebuilding subdivisions does not work. Fortunately, Krampus suggested a method how to deal with this problem. This post describes a variation of this theme.

Let us add genitals to the character in the previous post, and export the HD mesh to Blender as we did before.

When we import the character into Blender, we receive warnings that it was impossible to convert the HD mesh into a base mesh with a multires modifier. This happens because the HD export script exports the cached geometry with the body and the genitals already merged, and the merged mesh is not a clean subdivision.

We can verify that this happens manually. Add a multires modifier to the HD mesh and click Rebuild Subdivisions.

The tool fails with an error message. To import a HD character with geografts into Blender, we must use Krampus' method (or my variation of it). This is slightly more complicated than just pressing a button, but not terribly so. The basic workflow is this:

  1. Export the subdivided character without genitals with the HD exporter (Export HD To Blender), as we did in the previous post.
  2. Export the character with genitals with the base resolution exporter (Export To Blender).
  3. Import the character both with and without genitals into Blender.
  4. Merge the genitals with the HD character mesh.


Here we have imported the two scenes into Blender. We have three collections; two from the HD import and one from the import with genitals.


We will not need the base resolution meshes without genitals, so let us delete those objects immediately. The simplest way is to select the collection and select Delete Hierarchy in the right-click menu.


We next merge the armatures of those meshes that we intend to keep, in this case the HD body, the HD eyelashes, and the base genitals. Select the corresponding armatures and make the HD body armature the active one, and press Merge Rigs. This step is only strictly necessary if the geograft has special bones, which is the case in this case, but it never hurts.


Next select the HD body mesh and the base genitals mesh, and press Merge Geografts. Note that this button is located in the Finishing section. If you need to add morphs to the body or the genitals, as usual it must be done before we merge geografts.

The remaining objects in the collection with genitals have now served their purpose and should be deleted. As before, the simplest thing is to delete the entire hierarchy in the outliner.

And here is the HD mesh in Blender with genitals attached.