Curvature Map
Edge highlight + cavity shadow data
Definition
A curvature map is a baked texture encoding how convex or concave each pixel of a surface is. Convex edges (peaks) are stored as bright values, concave creases (valleys) as dark. Substance Painter's smart materials use this channel heavily to drive edge wear, dust accumulation in crevices, and paint chipping along ridges — effects that look procedurally correct because they follow the model's actual geometry.
In production
Bake curvature alongside normal and AO from the high-poly in Marmoset or Substance. Feed it into Substance Painter smart materials as a generator mask input, where positive curvature (convex edges) drives edge-wear and paint-chip generators while negative curvature (concave creases) drives dirt and grime accumulation generators. Curvature is typically baked at a shorter ray distance than AO since it's meant to capture fine surface detail like sculpted panel seams and rivets, not broad occlusion; Marmoset Toolbag exposes this as a separate curvature bake pass with its own cage settings independent of the normal map bake. A common pitfall is baking curvature from a low-poly mesh with hard edges and no supporting loops — the bake reads the low-poly's own triangulation as sharp curvature spikes, producing false wear lines along arbitrary triangle edges that have nothing to do with the sculpted high-poly. RizomUV and other UV tools can also derive a simplified curvature-like mask from mesh normals for quick previews without a full bake pass.
