Summary

Sculpting

The model's scale is off when exporting from ZBrush to a different program

This usually occurs when you export a mesh that's made completely in ZBrush, without a base mesh
- ZBrush uses Mystery Units™ and doesn't recognize the metric system
  - What ZBrush calls "scale" is actually the size of the ZTool's bounding box in Mystery Units™
  - This can make a mess when moving stuff between software with different default units
    - For example:

To fix this, once you are ready to export, go to Tool -> Export -> Scale
- If you use millimeters as a default, and want the conversion to be exact, you need to change the scale in ZBrush to be in the thousands - meaning, four (4) digits before the decimal point
  - Usually this means that you need to multiply it by 1000 (move the decimal point three places to the right)
In general, we use millimeters for everything, but other units should work as well - as long as they are always the same across all applications
- 1 unit -> scaled to 1000 units = 1000mm = 1m

If you use a base mesh you made in Modo and imported it to ZBrush, it should work fine
If you export as .OBJ, it should work fine
You can bypass this problem and still make your highpoly without a base mesh from start to finish in ZBrush by importing a 2x2x2m cube from Modo to Zbrush, and then appending your sculpts to the cube
- The cube can be ignored afterwards
  - The function of the cube is to initialize the ZBrush unit space to sync up with Modo
- After importing the cube, you can check the export scale, which should now show up in the thousands as it should

Mirrored UVs in Substance Painter

When baking mirrored UVs you can run into trouble with UV islands that are on top of each other
Move the mirrored UVs so that they are not on top of each other
If you have already textured the model in Painter and swap the model to a new version where the UVs have been updated this might ruin some hand painted areas so be aware of this

In case your model is black/has no textures, processing the meshmaterial usually fixes this
- Right-click model/type -> Locate type model resource -> find the corresponding meshmaterial -> right-click -> Process resource
- If that doesn't help, check that your FBX file doesn't have multiple Texture channels in Modo
If your asset appears transparent and dark in the Editor, check that your normal maps DON'T have alpha channel in them
- Also re-assign the textures and materials in Modo, and re-export the FBX
If the asset has a tintmask, check it's model component settings to make sure it's configured properly