Why do my normal maps appear to be inverted?
Most Max users are accustomed to using DirectX normal maps (even if they don’t realize it), however, by default Arnold relies on OpenGL normal maps to render correctly. If something appears to be incorrect with the normal map you’re using, this probably the issue. Luckily, there’s an easy fix.
In case you didn’t already know the difference between DirectX and OpenGL normal maps, DirectX reads green values as being Y down or negative, and OpenGL reads green values as Y up or positive. In Arnold, changing this is as easy as enabling the Invert Y checkbox in the Normal Map node.
As this is a frequently asked question we have provided both the question and answer in this thread.
