hi all,

this is the Lighting Report from Muppets Lab :)

I was able to reproduce the splotches, they occur under very specific conditions. Deviating from those conditions in any way smoothes the lighting results, and make the splotches go.

To make splotches I had to:

 - use point lights, with inverse square attenuation, at high intensity, nearby a wall, ceiling or other object in the scene. This setup creates extreme hotspots on the nearby object.

 - use IDL rendering at reduced quality settings. This propagates the hotspots around but fails to smooth them out.

So do note that it's not the light itself, but the hotspot it creates which causes the issue under lowQ IDL rendering. Of course, the issue can be avoided by

• not using IDL rendering
• not using point lights
• not using inverse square attenuation
• not using high intensity

but usually this conflicts with the scene you're building. When the pointlight is not in view of the camera (a bit behind, at the ceiling or wall) you will profit from making a big hole in there, so there is nothing to cast the hotspot. Ultimately, ramping up the quality settings help you out at the cost of extra render time.

LowQ is: bounces 2, irr caching 10, IDL quality 10, pixel samples 3. See image

HighQ is: bounces max (12, or up using the D3D FireFly render in scripts menu), irr caching 90, IDL quality 90, pixel samples 30. Just play with small renders to find the best quality / rendertime settings before going big. Note that when bounces go up, (ambient) lighting levels go up seriously so you have to adjust your light intensities accordingly.

I did not find that setting the Dist Start to anything made a difference (sorry Laurie), it still created the hotspots. Spotlights do not create hotspots, inverse linear attenuation seems to create a minor hotspot but not intense enough to create splotches at LowQ IDL rendering.

 

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though