Cavity Map
Fine crevice shadows
Definition
A cavity map captures small-scale surface concavities — the tight crevices where AO doesn't reach because of its broader sampling radius. Where AO darkens a deep cavity, cavity darkens the micro-detail inside it: scratches, fabric weave, screw threads. Multiplying cavity over albedo or roughness adds a layer of contact realism that purely AO-based shading misses.
In production
Bake cavity from the high-poly alongside curvature and AO in Marmoset Toolbag or Substance Painter's baker, typically as a grayscale pass derived from ambient occlusion at a very small sample radius combined with the mesh's curvature data. Most smart materials use cavity to drive grime accumulation inside fine details — a generator multiplies grime opacity by the cavity map so dirt collects convincingly inside a rivet or seam rather than sitting uniformly across a flat panel. A common bake artifact is cavity picking up unwanted noise from underlying high-poly sculpt detail that's too fine relative to the low-poly's texel density, producing a speckled, dirty-looking result; reducing the high-poly's surface noise or increasing texture resolution before baking usually resolves it. Curvature maps are frequently baked as a companion pass, but curvature captures convex edges as well as concave cavities, whereas a pure cavity map isolates only the recessed areas.
