ZBrush Normal Map Looks Wrong
Inverted or odd shading on a ZBrush normal map
Also known as: ZBrush normal map flip G · ZBrush normal map inverted · ZBrush normal map green channel · ZBrush Flip G · ZBrush create normal map · ZBrush normal map unreal
Quick answer
A ZBrush normal map looks inverted when its green channel does not match the target engine. In Tool > Normal Map, use Flip G to reverse the green channel, and Flip R or Switch RG if other channels are wrong, then create the map again and test it in the engine. Unreal Engine expects DirectX-style normals and Unity expects OpenGL-style, so choose the setting that matches. Also turn on Tangent so the map works on animated models.
How to fix it
A normal map in ZBrush is made from the lowest subdivision level compared with the highest, so the model needs clean UVs and a low base mesh. For most game pipelines the high-poly detail is baked in Substance Painter or Marmoset Toolbag instead, and ZBrush is used for sculpting and decimation. Whichever tool makes the map, decide the green channel convention once per project.
