AO & Curvature

Curvature and cavity maps drive most surface detail. Edge wear sits on the parts that stick out, dirt collects in the parts that sink in. Normally you bake these from a high-poly mesh, which means having the mesh, the cage and the baker to hand.

If all you have is the normal map, most of that is already in there, because how fast the surface turns is exactly what curvature measures. This works it out from the normal map and splits it into the raised and sunken parts, plus an approximate AO map from the same data.

Is this as good as a baked AO map?

No, and it is not meant to be. A real bake traces rays against actual geometry and catches one part shadowing another. This only sees the surface inside the map, so it finds creases and cavities but not contact shadows. For wear and dirt masks that is usually enough.

The AO is too dark.

Pull it back with Levels. AO dims ambient light, and too much of it reads as painted-on dirt rather than shading.

DirectX or OpenGL input?

Either works for AO, but curvature flips with the green channel. If the wear mask lands in the cracks instead of on the edges, run Flip Green first.

Related: ORM Packer · Levels · Flip Green