I'm trying to investigate the truth with huge amount of lights in Corona renderer.
Testing different scenes with Corona reveals some of strong sides of it along with the weakneses of course. Some of weakneses was our faults, but some of them are not.
In testing of night scenes I was found that increasing the lights amount has downside in increasing the noise amount. It may be normal, but time needed to remove this noise is terrible. In some cases it is few hours and tens hours and even more (
http://forum.corona-renderer.com/index.php/topic,2268.msg16956.html#new). But I found that some people managed huge amount of lights with no problem at all (
http://forum.corona-renderer.com/index.php/topic,1487.0.html).
In this case I started to investigate the problem in very simple scene with plane and 2500 light sources. With no GI at all. At default settings and 50 passes (to have nice DoF if needed) the noise is completely terrible in 11 seconds.
The next step is increased Light Samples Multiplier from 2 to 100 (max settings). This variant is noisy and waaaay too long to render - 7:00 min (if we keep in mind that it is plane with default material with no details at all). But as I know from real scene rendering if we have LSM that high the HD Cache is waaaay too long to compute.
Changing PT samples to 800 and LSM back to default (2) lead me to same amount of noise and time to render - 7:07, so nothing changed (except that HD Cache will compute much quicker in render with xxGI).
Well, does it possible at all to render this simple scene with no noise (even if we close our eyes on render times)? Heh. PT-200 and LSM-100 in 55 minutes... Nearly clean but not as Vray in 11 seconds (scene attached).
So. The main question is it really possible to render scenes with huge amount of lights in acceptable rendertimes? In huge amount of lights I mean not only Corona lights and dedicated light sources with emission, but even one plane with checker texture that creates huge amount of virtual lights. I ask all to particiate in testing of this scene to fing the truth!