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Import normal map question

ZBrush Usage Questions
#1

I can’t seem to figure this out properly.

I have a mesh which has a normal map. I load the mesh, import the texture, flip it vertically and apply it… thats fine.

I import the normal map, flip it and apply it, and don’t see any change to the mesh.

I tried creating subdivisions first, and still don’t see the normal map changing the mesh appearance.

In order, what is the proceedure for importing the normal maps and applying it so I see the mesh change with the normal map details?

(I want to redo some of the normal map to fix/change how it changes the model, so the idea is load the model, apply the normal map, resculpt changes, and then rebake the results and export the new normal map back out.)

#2

Zbrush doesn’t use any kind of real-time shader which make use of the normal map to change the appearance of the mesh.

Long ago it had a Zmapper plugin which could do this, but it was abandoned partly because different programs (Max, Maya, etc) all used different tangent basis at the time (there was no industry standard), so maps baked in one program wouldn’t look correct in others which could lead to people thinking something was wrong with their bakes or previews.

For what its worth, I’m not sure you’ll be able to do what you want to do even if zbrush could display the normal maps. Unlike Displacement Maps, Normal maps don’t actually contain any height information or data which changes the silhouette or surface of the model. The map data just says which direction any given point on a mapped surface should be facing in relation to the polygon’s own normal information, which creates an illusion when the light vector is factored in. The model itself is still just as flat/smooth as it is without a normal map applied. This also means that if you start to change the model’s vertex normals around by physically sculpting the model around, then the old normal map’s information is no longer accurate for this new dataset.

Your best bet is to look into a program like Substance Painter. Where Zbrush is focused on sculpting models and pushing points around, Substance Painter is meant for working on all the various maps that real-time shaders make use of. This program will let you preview a normal map on a model and give you the option to paint on top of it. You will also be able to paint in channels which will can modify the final normals (since you’re just painting, not sculpting and changing the mesh around).

#3

Yeah, I’m remembering the old plugin you mentioned. I’ll just change my target work plan.
Thanks for the clarifying reply!