V-Ray Tip: Disable Region Feathering for Seamless V-Ray Patch Renders

When fixing small areas with a re-render, use a render region with blur/feather disabled to avoid visible seams and artifacts at the patch boundary.

Why disable region blur/feather:

• Pixel-accurate edges: Feathered regions blend partially sampled pixels and can create halos where the new patch meets the original frame.
• Denoiser integrity: Per-region denoising can generate a different noise texture and variance near the edge, producing a ring or softness shift.
• Post-effects consistency: Lens effects, sharpening, LUTs, and tone mapping may evaluate differently on a cropped/feathered patch, amplifying mismatches.
• Compression visibility: Any subtle mismatch is accentuated by delivery codecs and web compression, making seams easier to spot.

Recommended workflow for clean patch renders:

• Match the original: Keep GI engine(s), noise threshold, Max Subdivs, Adaptive Lights, RTX, clamp settings, and color mapping identical to the original render.
• Set Feather/Blur to 0: In the V-Ray Frame Buffer (VFB) Region tool, set feather to 0 px and draw a tight region that extends a few pixels beyond the changed area.
• Prefer Render Mask for precision: Use Render Mask (Selected/Include list) to limit shading to the target object(s) while still rendering the full frame for stable post and AOV alignment.
• Control denoising: Either disable denoising for the patch and denoise in comp on the final stitched frame, or ensure the denoiser operates in full-frame mode with identical parameters.
• Disable Lens Effects in-render: Turn off bloom/glare in VFB for the patch; reapply lens effects in comp or via a full-frame pass to maintain consistency.
• Export robustly: Save 16/32-bit multilayer EXR with the same color space (sRGB/ACES), include Light Select, Cryptomatte, and utility passes, and keep highlights unclamped.
• Stabilize randomness: For progressive workflows, lock the noise pattern or use Bucket mode to match the original grain and sampling distribution.
• Light Mix parity: If Light Mix drove the final look, include Light Selects and reapply the same mix or exposure values in comp.

Platform notes (V-Ray VFB2 in 3ds Max, Maya, SketchUp, Rhino):

• Region: Click the Region icon in the VFB, open options, and set Feather/Blur to 0 before drawing the box.
• Crop vs. Mask: Use Crop only for previews; for production patches, keep full-frame with Render Mask to guarantee coordinate and AOV alignment.
• Effects updates: Ensure effects are evaluated consistently (avoid per-region effects-only updates when producing finals).

Quality checks before delivery:

• Use VFB History A/B to compare edge continuity at 200–400% zoom.
• Inspect Sample Rate and Denoiser Confidence passes along the region border for abrupt changes.
• Test with the client’s LUT/grade to confirm no haloing or exposure jumps.

Troubleshooting seams:

• Edge ring after comp: Re-render the patch with denoiser off; denoise the final composite instead, or re-run denoising full-frame.
• Specular mismatch: Align clamp settings (on or off) between original and patch; mismatched highlight roll-off causes visible joints.
• Noise mismatch: Tighten noise threshold or match Max Subdivs; ensure RTX/Adaptive Lights settings mirror the original.

Pro tip: Create a “Region Patch – No Blur” preset and a VFB layer tree preset for your studio. Standardizing this prevents last-minute artifacts and saves iteration time.

For licensing, upgrades, and expert guidance on Chaos V-Ray, visit NOVEDGE. Explore bundles and support at NOVEDGE.com or reach their specialist team for tailored advice.