V-Ray Tip: V-Ray GI Workflow for Balanced Exterior-to-Interior Lighting

Quick, reliable tweaks to balance global illumination when a scene contains both bright exteriors and shaded interiors.

Core setup

• GI engines: start with Brute Force (primary) + Light Cache (secondary) for stills; switch to Brute Force + Brute Force for challenging glass-heavy spaces or animation stability.
• Lighting: combine Sun & Sky with an HDRI Dome using Adaptive Dome Light; skip legacy light portals when ADL is on.
• Glass: enable “Affect Shadows” in VRayMtl for window glass to keep interiors from going murky without cranking exposure.
• Camera Imager: use Exposure and Highlight Burn (0.2–0.6) to retain exterior highlights while revealing interior detail; set White Balance to a neutral reference.
• Scale and units: correct scene scale is essential for realistic GI bounce range and light intensity.

GI tuning where indoors meet outdoors

• Light Cache (as secondary GI): 1200–2000 samples for large archviz; enable Retrace (2–4) to fix leaks and dark corners; Pre-filter 10–20 to smooth blotches in stills.
• Adaptive sampling: Noise Threshold 0.01–0.02 for look-dev, 0.005 for finals; Min Shading Rate 6–8 to stabilize glossy/SSS.
• Max Ray Intensity: 10–20 to tame fireflies from windows and metals without crushing energy; leave “Clamp output” off for linear workflows.
• Adaptive Lights: keep on in scenes with many luminaires to accelerate GI.
• GPU notes: use Light Cache secondary on GPU for interiors; enable On-demand Mip-mapping for big textures and set Max Ray Intensity similarly.

Windows, materials, and exposure interplay

• Window glass: keep it thin (or use Thin-walled) for architectural glazing; heavy fog color/multiplier will overly darken interiors.
• Interior materials: avoid albedos above ~0.8–0.9; overly bright walls bounce unrealistic energy and break the contrast between indoors and outdoors.
• Camera: favor realistic shutter/ISO and use VFB Exposure for fine trims; lock Auto Exposure/White Balance before animation to avoid flicker.

Environment overrides for balance and speed

• Use GI/Reflection/Refraction overrides: a slightly blurred GI HDRI plus a high-res Reflection HDRI preserves crisp reflections without oversampling GI.
• For exteriors through windows, raise Sun intensity modestly (1.2–2.0) or adjust LightMix instead of pushing global exposure.

Debug fast, iterate faster

• Material override (clay): isolate lighting/GI problems quickly; exclude glass and emissives from the override.
• Render Elements: add GI, Lighting, RawGI, RawLighting, Reflection, Refraction, and Denoiser to diagnose bounce imbalance and noise sources.
• Animation: enable Light Cache “Use Camera Path” for fly-throughs; for moving objects/lights, prefer Brute Force + Brute Force.

Suggested starting values

• CPU stills: BF + LC; LC Samples 1500; Retrace 3; Pre-filter 15; Noise 0.007–0.01; Min Shading Rate 6; MRI 15.
• GPU stills: BF + LC; On-demand Mip-mapping on; Noise 0.01; MRI 10–15; Adaptive Dome Light enabled.

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