V-Ray Tip: Refraction Max Depth for Layered Glass

Layered glass stacks (double/triple glazing, bottles-in-bottles, display cases) require higher refraction depth to trace enough ray transitions. If you see black patches, unnaturally dark glazing, or missing objects behind glass, increase the refraction depth.

• What “refraction depth” controls:
  • The maximum number of refractive interfaces a ray can pass through before it stops.
  • Each air–glass or glass–air boundary counts as one refraction event.
• Quick rule of thumb:
  • Single pane: 2 refractions (air→glass, glass→air).
  • Double glazing: 4 refractions.
  • Triple glazing: 6 refractions.
  • Glass with liquid: add the glass↔liquid boundaries as well (often 6–10 total).
• Where to set it:
  • Per material: VRayMtl “Refraction Max Depth” (Depth). This is the most precise approach for glass-only tweaks.
  • Globally: Render Settings/Setup → V-Ray ray tracing/optimizations → “Refraction Max Depth.” Use this to establish a safe baseline for the whole scene.
• Practical starting values:
  • Single glazed windows: 2–4.
  • Double/triple glazed facades: 6–8.
  • Showcases, bottles, shower enclosures with overlaps: 8–12.
  • Complex nested dielectrics (liquid in glass, multiple shells): 12–16.
• Don’t forget reflections:
  • Glass benefits from matching or slightly lower Reflection Max Depth (e.g., Refraction 10, Reflection 6–8) to avoid excessive cost while maintaining realism.
• Performance tips:
  • Increase depth only for materials that need it; keep global values moderate.
  • Use Render Masks/Regions to iterate on problematic areas before committing to full frames.
  • Pair with a sensible Noise Threshold; don’t overcompensate with extreme depths if the shot doesn’t require it.
  • Use denoising on finals, but always save a non-denoised EXR for comp.
• Visual accuracy pointers:
  • Correct IORs: typical glass IOR ~1.5; liquids vary (e.g., water ~1.33). Wrong IORs can mimic low-depth artifacts.
  • Enable “Affect Shadows” on glass to prevent unnaturally dark interiors behind glazing.
  • For colored glass, use absorption/fog color with correct scene units so thickness looks physically plausible.
• Troubleshooting checklist:
  • Black/dark panels or missing objects behind glass → raise Refraction Max Depth.
  • Unexpected bright clamping/sparkles → clamp HDRI output and review light intensities before pushing depth higher.
  • Noise in heavy glazing → raise light quality selectively and verify adaptive sampling before adding more depth.
• Pipeline considerations:
  • For V-Ray GPU, ensure the GPU ray trace depth settings match your material needs; consider CPU fallback when memory is tight.
  • Document per-material depth overrides using your team’s lookdev notes or embed an image stamp in the VFB for handoff.

Need guidance selecting the right V-Ray edition or building a glass-heavy visualization pipeline? Consult the experts at NOVEDGE for licensing and workflow advice, or explore Chaos V-Ray solutions via NOVEDGE to keep your studio render-ready.