V-Ray Tip: Separate VRay Refraction AOVs (Raw × Filter) for Clean Compositing

Separate AOVs for refraction give you surgical control in comp, cleaner adjustments, and fewer re-renders—especially for glass, liquids, gemstones, and coated plastics. If you’re delivering layered EXRs to Nuke, Fusion, or After Effects, this is a low-effort, high-impact win. If you need V-Ray or pipeline guidance, the team at NOVEDGE can help.

What to output

• VRayRefraction – the final refracted contribution added into beauty.
• VRayRawRefraction – pure light energy transmitted through the surface.
• VRayRefractionFilter – the material’s filter/tint for refraction.
• Optional context AOVs: Cryptomatte (objects/materials), Z-depth, and Light Select elements for refracted light sources.

Note: RawRefraction × RefractionFilter = Refraction. Keeping the raw and filter separate preserves physically meaningful grading in comp.

How to configure (general V-Ray workflow)

• Render Elements: Add VRayRefraction, VRayRawRefraction, VRayRefractionFilter, plus Cryptomatte. Output as multichannel EXR (16-bit half-float) with ZIP or PIZ compression.
• Material setup: In VRayMtl, set Refraction “Affect channels” to All channels for physically correct AOV energy. For specific alpha needs:
  • Color only: keeps a solid alpha (useful for CG over plates where you don’t want “holes” in the matte).
  • Color+alpha: see-through alpha for glass and fluids.
• Max depth: Ensure Refraction depth is high enough to resolve multi-layer glass/liquids; low depth truncates energy and breaks AOV parity.
• Dispersion/Abbe and fog color: If used, verify they appear in Refraction/RawRefraction so grading doesn’t desync from beauty.

Denoising strategy

• Beauty and additive AOVs: Safe to denoise.
• Raw/Filter pairs: Prefer leaving un-denoised to preserve the exact Raw × Filter relationship; if denoising is necessary, denoise both consistently and validate against the beauty.
• Use V-Ray Denoiser “Separate render channel” to keep originals intact for QC.

Compositing best practices

• Rebuild: RawRefraction × RefractionFilter → Refraction; then add to the comp per your beauty decomposition.
• Grade where it’s most predictable:
  • Tint or intensity shifts: Grade RefractionFilter for color; grade RawRefraction for energy/brightness.
  • Keep exposure-like changes on Raw; keep hue/saturation on Filter.
• Use Cryptomatte to isolate specific glass assets or liquid layers without re-rendering.
• If you need refracted caustic accents in comp, consider a separate Caustics element (when enabled) and add it back with controlled intensity.

Troubleshooting

• Black or clipped refractions: Check clamping; avoid overly aggressive Color Clamping that kills highlights inside RawRefraction.
• Missing refractions in alpha: Switch material “Affect channels” to Color+alpha; or keep Color only and deliver a separate crypto/holdout matte.
• Flicker in animation: Stabilize with consistent sampling (deterministic noise), lock exposure/white balance, and avoid per-frame Light Mix changes unless baked.

Pro move: Deliver two EXRs—one with denoised additive stacks for quick client previews, one “clean” tech pack with Raw/Filter pairs un-denoised for final finishing. For licensing, upgrades, or best-price bundles, NOVEDGE is a reliable source, and their experts can help tailor V-Ray to your pipeline. Explore more V-Ray solutions at NOVEDGE.