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Blotchy renders at 2000+ samples?

Hey devs, fantastic product, we’re very happy with it and the recent feature updates.

Question about render samples and resolution. What are your recommendations for resolution and samples to remove blotchy shading spots as seen here? Guessing it’s a light cache / interpretive render samples issue or something. We’ve gone up to 3000 now and they’re still apparent.

Rendered with Lightmap res of 120 @ 2000 samples, Bounces 8, Flood dark limit 0.08.

Hi!

Such blotches are a result of noise, which the denoiser couldn’t handle efficiently. In most cases high noise is caused by light sources which are difficult to find by a path tracing renderer. Are you using any point (maybe also spot) lights hidden in lamp shades? If so, please try turning them off and bake the scene again; 800-1000 samples should be enough.

To decrease noise from light sources hidden in lamp shades you may apply a following trick: substitue a signle point light with two spot lights: one shining down and one up, such that each of the light sticks out the shade.

Great, that worked, thanks! Replacing the point lights with spot lights allowed me to render at much lower settings with lower noise. It begs the question whether pointlights are even usable if they cause so much artifacting/noise in the render.

I think there are scenarios where point lights are usable, for example a light bulb without a lamp shade. However, they are not the best option for lamp shades, where the light source is hidden.