V-Ray Tip: V-Ray Anisotropy Techniques for Brushed Metals and Hair

Anisotropy stretches reflections along a preferred direction—essential for believable brushed metals and hair. Here’s how to dial it in with confidence.

• Brushed metal workflow
  • Start with VRayMtl using a GGX BRDF. Use Metallic workflow (Metalness 1.0) or a physically plausible IOR for legacy setups.
  • Set Roughness in the 0.15–0.35 range for common brushed finishes. Then increase Anisotropy to 0.4–0.8 to elongate highlights.
  • Control highlight direction with Anisotropy Rotation. Drive it by UVs for paneling, and by radial UVs for lathes, knobs, or discs. If UVs are poor, create a dedicated flow map to steer the rotation.
  • Add a fine directional normal/bump to reinforce the brushing. Subtle micro-scratches at a different angle add realism without overpowering the main direction.
  • Introduce slight roughness variation to avoid banding—use a low-contrast noise or a brushed texture as a mask.
  • For anodized or lacquered metals, keep the base metal anisotropic and add a thin coating layer for the clear finish.
  • Tip: Avoid TriPlanar for direction-critical surfaces; it breaks coherent highlight flow. Proper UVs are key.
• Hair and fur highlights
  • Use VRayHairMtl. It inherently aligns specular lobes with strand tangents, producing realistic anisotropic glints along hair flow.
  • Shape the look with Primary and Secondary specular lobes: narrower primary for crisp glints, slightly wider secondary for the broader sheen.
  • Drive variation with per-strand attributes or material randomization to avoid uniform sparkle. Small random roughness offsets go a long way.
  • Balance Transmission for backlit shots to reveal fiber structure without washing out specular detail.
• Sampling and stability
  • Anisotropy can be noisier than isotropic gloss. Target a Noise Threshold of 0.015–0.02 for finals; let adaptive sampling do the work instead of cranking fixed subdivs.
  • Enable the V-Ray Denoiser in VFB for cleaner iterations; use per-element denoising for reflections if available.
  • Use Max Ray Intensity clamp (e.g., 2–4) to tame hot glints and prevent fireflies, especially with small lights and HDRIs with tiny emitters.
  • Inspect Reflection/Specular and Light Select render elements to evaluate highlight shape and direction before committing to full frames.
• Direction control tricks
  • Rotation maps: a grayscale-to-angle remap can steer highlight direction across a surface for complex brush patterns.
  • Cylindrical objects: unwrap with radial UVs so anisotropy follows the lathe marks. For linear panel brushing, keep UVs aligned to world axes.
  • Scale matters: set scene units to real-world sizes; anisotropic highlights scale with roughness microdetail.
• Pipeline tips
  • Iterate with IPR to judge highlight flow under camera motion—directionality pops once the object or camera moves.
  • Save layered EXRs and keep Reflection/Specular passes exposed for subtle comp-level tuning of glints.

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