V-Ray Tip: Save beauty and AOVs into a single multi-channel EXR

Saving the beauty pass and AOVs as a single multi-channel EXR is the most reliable way to keep renders compact, flexible, and production-ready for compositing.

Why multi-channel EXR

• One file per frame with all AOVs embedded (beauty, lighting, masks, utility) reduces file sprawl and relinking headaches.
• High dynamic range in linear color ensures precise grading, relighting, and VFX integration.
• Lossless compression options keep storage efficient without sacrificing quality.
• Broad DCC/comp support: Nuke, Fusion, After Effects (via ProEXR), Resolve, and more.

Recommended V-Ray VFB setup

• File format: OpenEXR (.exr), enable “Save all image channels to a single file.”
• Bit depth:
  • 16-bit half-float for most shots (smaller files, ample precision).
  • 32-bit float for extreme HDR highlights, heavy Light Select relighting, volumes, or lens effects.
• Compression:
  • PIZ for balanced quality/speed (great default).
  • ZIP for consistent results on flat graphics or masks.
  • DWAA/DWAB for animation sequences when mild lossy compression is acceptable.
• Color management: Render linear in sRGB or ACEScg; use OCIO in the VFB for viewing. Save renders untonemapped; export a LUT if you need to preview the look in comp.
• Denoiser: Add a Denoiser render element and save both raw and denoised AOVs for maximum flexibility.
• Channel naming: Keep default V-Ray names or apply a consistent prefix scheme so compositors can script channel extraction easily.

Must-have AOVs to include

• Light Selects (Diffuse/Specular/Emission) for targeted relighting.
• Cryptomatte (object/material/asset) for zero-aliasing mattes without preplanning IDs.
• Raw Lighting/Raw GI/Reflection/Refraction and their Filter/Color counterparts for full beauty reconstruction in comp.
• Z-Depth (set depth range thoughtfully), Normals (world), Position/UV where relighting or projections are expected.
• Material/Render IDs only if your pipeline still relies on them alongside Cryptomatte.

Size and performance tips

• Only enable AOVs your comp actually needs; extra channels add up quickly in storage and I/O.
• Prefer half-float plus PIZ for most work; switch to 32-bit for extreme HDR or complex relighting.
• Leave highlights unclamped for realistic bloom/glare in comp; clamp only if fireflies persist after addressing light/material causes.
• Consider Deep EXR only if your DCC and comp pipeline benefit from it—file sizes can grow significantly.

Compositing workflow notes

• Ingest the multi-channel EXR and shuffle/extract channels as needed; build your beauty from Raw/Filter pairs when precise control is required.
• Use Cryptomatte to isolate elements without re-rendering. Light Selects enable scene relighting and shot continuity fixes.
• Grade in linear, then apply your display/view transform last (e.g., sRGB or ACES Output Transform).

Pipeline hygiene

• Adopt structured naming with versioning and tokens for scene, shot, layer, and frame indices.
• Embed metadata (frame stamp, camera, color space) and maintain a simple README for compositors.

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