V-Ray Tip: Tuning VRaySun Size Multiplier for Soft, Physically Plausible Shadows

Quick tip: get physically plausible, art-directable soft shadows by tuning the VRaySun “Size multiplier.”

What it does

• The Size multiplier controls the apparent angular diameter of the sun disk. Larger values turn the sun into a bigger area light, broadening the penumbra and softening shadow edges.
• Default 1.0 approximates the real sun. Increasing the value softens shadows; decreasing it makes them crisper.
• Softening direct shadows also lowers overall contrast; plan for minor exposure/lighting tweaks to keep energy balance.

Where to find it

• 3ds Max: VRaySun > Modify > Size multiplier.
• Maya: vraySunShape > Size multiplier.
• SketchUp / Rhino: V-Ray Asset Editor > Lights > Sun > Size multiplier.

Practical ranges (start points)

• 0.5–1.0: Crisp, high-noon exteriors with defined shadows and strong contrast.
• 2–5: Late-afternoon “golden hour” softness with believable penumbras for architecture and product hero shots.
• 8–20: Hazy days or stylized softness; useful when you need gentle, forgiving contact shadows for people and foliage.

Balance exposure and color

• As Size increases, direct light intensity per unit area decreases. Compensate with +0.3 to +1.0 EV on the V-Ray Physical Camera or nudge Sun intensity (1.1–1.8x) to maintain your key level.
• Pair with VRaySky controls:
  • Turbidity 2–3 for clear skies; 4–6 for hazier, softer lighting.
  • Adjust Ozone to fine-tune sky hue; raise slightly for cooler skylight when chasing soft, overcast vibes.

Quality vs. performance

• Bigger light sources often reduce high-frequency shadow noise; you can relax Noise Threshold slightly (for example 0.015–0.02) while retaining clean results.
• Use Progressive for look-dev and switch to Bucket for finals once the Size multiplier is locked.
• If shadows look too “mushy,” lower Size incrementally (5 → 3 → 1.5) and re-check contact areas at hero camera distances.

Look-dev checklist

• Set camera exposure first; then iterate Sun Size to taste.
• Evaluate penumbra width on mid-distance objects (5–20 m) to judge realism quickly.
• Keep scene units and scale accurate; incorrect scale skews perceived softness and GI behavior.
• For aerial haze and depth cues, add VRayAerialPerspective; it complements larger sun sizes beautifully.

Mini recipes

• Crisp architectural noon: Size 1.0, Turbidity 2.2, ISO 200, f/8, 1/200s.
• Warm golden hour: Size 3–5, Turbidity 3.5–4.5, slight white-balance warm-up.
• Soft stylized: Size 10–16, Turbidity 5–6, mild exposure boost, subtle Bloom/Glare.

Pro tips

• Use Interactive Rendering to iterate; changes to Size multiplier update immediately.
• Lock consistency across shots: once approved, keep the same Size per sequence for continuity.
• Combine with Light Select AOVs and VRayLightMix for intensity/color tweaks; re-render only when changing Size.

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