V-Ray Tip: Curvature and AO Masks for Realistic Material Wear

Smart use of curvature and ambient occlusion (AO) masks can add believable wear, dirt, and depth to your materials with minimal texture overhead.

What and why:

• Ambient Occlusion (AO): simulates contact shadows in crevices and between close surfaces. Great for grounding assets and enhancing detail readability.
• Curvature: detects convex (edges) and concave (cavities) regions of geometry. Ideal for edge wear, polish, chipped paint, and cavity grime.

How to set them up in V-Ray:

• AO with VRayDirt
  • Use a VRayDirt texture as a mask or through a VRayExtraTex render element.
  • Radius: set in scene units; start with 1–5% of the object’s largest dimension. Too large = muddy; too small = speckled.
  • Double-sided: on for thin meshes; use “Consider same object only” to avoid cross-object darkening when needed.
  • Occluded/Unoccluded colors: drive masks (white for cavities). Invert when you need cavity-only vs. contact-only effects.
  • Transparency/Affect reflections: enable when AO should respect glass/translucent surfaces and reflective contribution.
• Curvature with VRayCurvature (or equivalent)
  • Convex mode to isolate outer edges (polish/paint rub-off). Concave mode for grime in recesses.
  • Radius in world units; keep it proportional to scale and consistent across assets.
  • Clamp/contrast: soften intermediate values to avoid harsh, posterized masks.
• Render elements for lookdev/compositing
  • Add VRayExtraTex AOVs with VRayDirt/VRayCurvature plugged in to export clean masks per pass.
  • Use multi-layer EXR and named AOVs for pipeline-friendly outputs.

Practical layering recipes:

• Edge wear: Curvature (convex) → drive a Blend/Layered material to reveal a rougher, less metallic undercoat on edges.
• Cavity grime: AO or Curvature (concave) → multiply into base color; add to roughness to mute micro-reflections in crevices.
• Polish/handling: Invert curvature on frequently touched areas to slightly reduce roughness and increase specular level.
• Break repetition: Combine AO/Curvature masks with a low-contrast noise (e.g., VRayNoise) for organic variation.
• Triplanar and UDIMs: Keep masks procedural via triplanar; bake to UDIMs only for real-time or heavy scenes.

Performance and robustness:

• Scale matters: confirm correct system units; AO/Curvature radii are world-based.
• Avoid extremes: never clamp to pure black/white; preserve midtones for subtle blends.
• Bake when needed: for crowds, large assemblies, or animation, bake AO/Curvature to textures to stabilize flicker and reduce eval cost.
• GPU rendering: verify node support on your version; if unsupported, pre-bake masks or route via VRayExtraTex AOVs.
• Troubleshoot noise: if AO introduces speckles, reduce radius, increase samples, or isolate the noisy AOV with VRayExtraTex and adjust locally.

Workflow tips:

• Work in linear/ACEScg; view through sRGB/OCIO to judge mask softness correctly.
• Name and version masks; store presets for AO/Curvature radii to keep consistency across assets.
• Document mask intent (edge, cavity, contact) in your material graph for quick handoffs.

Looking to sharpen your V-Ray texturing workflow or upgrade your license? Explore V-Ray options and expert guidance at NOVEDGE. For broader design software needs and bundle opportunities, visit NOVEDGE.