Hello again,
I’m quite confused about the difference between these two screenshots. The only change in both is the emission value on the PBR material—it’s set to 0.50 in one and 0.51 in the other. I can’t figure out where that “darker heart-shaped” shade in the marble is coming from.
Thank you!
PBR_MATERIAL.3dm (9.5 MB)
Thank you @David53 for looking at it… I changed the subject of this discussion . because I tested too with an emmiter material (no PBR) and that happens too… the strange thing is that only happens right after “0.51” value set… and it remains visible until… a 20 aprox… I tested too with a simpler scene… no marble and simplified geometries (even modeling a gap because I thought it was an geometry interference)… but until now my gues is a bug in Emmission Materials
PBR_MATERIAL_SOLO EMISION.3dm (9.0 MB)
From quick check it appears to be the rectangular light that shows up in the lower sphere. I am not sure what is going on, probably some set of conditions that show in the conversion of the plaster material. As a work around convert the plaster material of the bottom sphere to PBR, select Opacity from the detailed section and set opacity to 0.999.
I mark this topic so I remember to log at least a bug next week.
okok… thank you… I’ll do that in the meantime…
Hi Again.
ok… I don’t know if this is also something related to that bug… but I just don’t understand why is it that lowering the emission value of the material of the lamp. brightens the scene. (well in general the scene setup with the different lights is difficult to understand… tuning down sometimes one light. brightens everything else… etc.) … also for instance in another attempt I tried to use a spotlight… and on some circunstances it would cast also shadow (in the screen shot you can see that the re is a “shadow” cast right form the origin of the spotlight… Once again that became evident only on some specific intensity values.
Thank you … any advice highly appreciated
This has happened to me frequently, until I got in the habit of just not trusting anything the Viewport is telling me without conducting the chain:
Raytraced → Shaded → Raytraced.
It’s an odd behaviour. In early days, it felt like the scene lighting was being “normalised” for some reason. But then on a forced complete viewport refresh, the scene would return to normal.
Does this work on your end, or is the behaviour persistant? Your not the first person to see this really odd behaviour.
When you see this behaviour, what you can try is to just leave the viewport in the state you think is wrong, and then hit the “Render” button. See what the render window gives you compared to viewport.
Thank you David… I’ve tried your suggestion… but still the same results… also on render… reseting. .closing viewports… etc. Same odd behaviours… But I just found out that the point light is causing the bug in this scene of today… . Just disabling it, and both the spotlight and the emitter material started to work more consistently… So … my conclusion here… point light bug… (but the original heart shapped shade still a mistery)…
I wanted to ask too if there is a limit on how many lights can Cycles handle… . an also if the intensity values have any “understandable” logic … because sometimes lights I have to tune them with number as high as 5000… but I would like to know if I can “guess less”… (actually even muuuch larger numbers if the light is “inverse squared fall off”)
Thank you
I think this is related to bug RH-65742 Emissive materials affect linear light intensity in a scene
One of those bugs I haven’t found a solution for as of yet, unfortunately 
Bug is not open for public, because it contains confidential material, but I link this topic to the report.
There should be no limit - I have tested with 10k lights.
Hi Nathan,
Ok, good to know. Nonetheless, I’m not sure if the emitters were causing the problem. I’m not sure if this is the same bug or a different one—you’ll probably be able to assess that better than me. I’ve purged all emitter materials from the file, but the point light still causes the spotlight to behave as if it has negative values (casting shadows instead of light).
I’m uploading the file here in case it helps. It could also be that something in my file is misconfigured.
LAMPARITA small 2_no emitters.3dm (1.5 MB)
The problem in the very least is the usage of lights with constant energy level (no fall-off). There indeed is something weird with the overlapping lights, but setting the two lights to linear that are currently constant, then toggle the Raytraced view you get:
Note the spotlight is now correct.
