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Going from lowpoly to highpoly… and baking maps

ZBrush Usage Questions ZBrush 2022 Usage Questions
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#1

I have a uv mapped, retopologized lowpoly model of a female character.

I wish to create a highpoly version of this character, sculpt details like wrinkles so I can bake these maps onto my lowpoly model.

How would I do this? Do I just import the OBJ of my lowpoly into zbrush, subdivide a few times, sculpt details, then import both lowpoly and highpoly into substance painter and make+bake in there?

Did I make a mistake making the lowpoly first? The tutorials I’ve looked at all go from high to low poly and not the other way around.

Getting texture and low poly, from a high resolution mesh with polypaint, workflow
#2

Hello @Luulaalaa_A

Generally, yes you’d import your model, subdivide sufficiently for the desired level of detail, then create and export maps based on the high resolution detail either manually or with Multi Map Exporter.

However, there are a few things to look out for.

  1. Make sure to select the polymesh 3d star from the Tool menu as an import target when first importing your mesh. If you import it with any other tool active your model will inherit its export scale settings and potentially cause a scale shift.

  2. We recommend working without UVs while you sculpt. Uvs significantly increase the file size of high resolution geometry and provide additional opportunities for issues. If you delete the UVs from your model, you can restore them by re-importing your base level OBJ into your tool at the lowest subdivision level.

  • We actually recommend not even creating UVs until all your sculpting work is done, as this will lock you to that topology in order to keep from breaking the UVs. Much of the power of ZBrush’s toolset comes from the ability to quickly change topology on the fly. If you are locked into that topology you won’t be able to use these features.
  1. The act of subdividing a mesh with subdivision smoothing active will subtly alter the form of the mesh at all levels of subdivision. This is important to be aware of if you are generating the displacement map in ZBrush, as the base level geometry will no longer be exactly the same. So if you take that map generated for the altered base level mesh and apply it to the original unaltered mesh in another program this is likely to result in issues with the map display.
  • So you would need to either export the altered base level geometry directly from ZBrush and apply the map to it, or you would need to restore the form of the original geometry immediately prior to generating the maps. The procedure for doing this involves storing a morph target and re-importing your original geometry into it. This is described both in the “Switch MT” section of the MME documentation (linked above) and in the basic texture creation documentation.

Good luck!