V-Ray Tip: V-Ray AOV Best Practices for Physically‑Based Compositing

AOVs (Render Elements) give you the control to re-balance lighting, materials, and effects in comp without re-rendering. Set them up once, and you unlock faster look-dev, safer client revisions, and cleaner deliveries.

Export these core AOVs for a robust, physically based composite:

• Beauty (for reference only, not your final comp driver)
• Diffuse Filter, Raw Lighting, Raw GI
• Reflection Filter, Raw Reflection
• Refraction Filter, Raw Refraction
• Specular/Coat (as applicable), Emission, SSS
• Atmosphere/Environment (fog, volume)

Utility AOVs that dramatically increase flexibility:

• Cryptomatte (objects, materials, assets) for clean mattes in Nuke/AE
• Light Select (by light or groups) for relighting and LightMix parity
• Z-Depth (linear), Normals (world), Position (world)
• Velocity (motion vectors) for post motion blur
• Denoiser outputs (RGB and Variance) for blendable noise reduction
• MultiMatte/Material ID where Cryptomatte isn’t an option

Recommended formats and color pipeline:

• Multi-channel OpenEXR, 32-bit float, ZIP or PIZ compression
• Scene-linear in sRGB/ACEScg as per pipeline; avoid clamping
• Keep tone mapping/view LUTs in VFB for preview only; don’t bake them into AOVs. Save VFB corrections/LUTs separately to reapply in comp.

Recombination guide (typical energy-preserving workflow):

• Diffuse = Diffuse Filter × (Raw Lighting + Raw GI)
• Reflection = Reflection Filter × Raw Reflection
• Refraction = Refraction Filter × Raw Refraction
• Beauty ≈ Diffuse + Reflection + Refraction + Specular/Coat + SSS + Emission + Atmosphere

Setup tips that save time (and re-renders):

• Enable Light Select passes that match your LightMix groups; use “direct” or “full” per your comp plan.
• Limit the number of per-light AOVs—group by function (key, fill, rims, accents) to manage file size.
• For animation, prefer Velocity + post blur to avoid long render-time MB; validate shutter equivalence.
• Z-Depth: keep far/near consistent across shots; comp with camera-space linear values for stable fog/DOF.
• Cryptomatte: ensure stable naming and IDs; avoid per-shot renames that break mattes.
• Denoiser: output the denoised RGB as a separate AOV; keep the raw passes untouched for maximum control.

Performance and storage:

• Only add AOVs you will use; each pass adds memory and I/O.
• Consider 16-bit half for non-HDR utility passes (Normals, IDs) to reduce size; keep lighting in 32-bit float.
• Test a representative frame for AOV integrity before sending a full sequence to the farm.

QC checklist before delivery:

• No clamped highlights; linear EXR opens at gamma 1.0
• Beauty reconstructed from AOVs matches within acceptable tolerance
• Premultiplication handled consistently; supply alpha and note premult state
• Consistent pass naming across shots and episodes

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