VRayEnvironmentFog Texture Lights Severe Noise

[White Wizard]

I've noticed that texture lights such as vraylightmtl but also vraylight spheres and similar cause a dramatic increase in fog noise that is virtually impossible to clean up. I've since replaced all of these lights with simple Vray disc lights which produces a major difference in fog quality closer to the light source.

Is this an expected limitation? There is also the possibility that I'm missing a setting to remedy this but I didn't have much luck finding similar issues via searches.

I believe IES lights might also cause the large blocks of noise but have not confirmed as I deleted them early in my project. One other thing I'd like to add is that "simple" texture lights (lightmtl with no texture but a simple color output or even a sphere light) cause the large blocky noise about as much as bitmapped lights.

I've had this issue with Vray 3.3 and 3.4.

[Svetlozar Draganov]

Would it be possible to attach some screenshots so we could better understand the noise differences?
If you could provide same scene for investigation it would be even better.

[White Wizard]

Would it be possible to attach some screenshots so we could better understand the noise differences?
If you could provide same scene for investigation it would be even better.

Here are two variations of the same scene with exactly the same settings. The difference being that one scene was rendered with vraylightmtls and the other was rendered with vraylights set to disc shapes.


Notice the severe difference in render times but also in quality. To get the noise in the vraylightmtl fog down to the level in the vraylight example, my render needs to run for close to an entire day. Upping the subdivs on the vraylightmtl with lcoal subdivs enabled does help slightly but after a certain point it experiences severely diminishing returns.

EDIT: Also forgot to mention I'm not using GI. I remember reading somewhere that textured lights are recommended to be used with GI to lessen the noise. I'm assuming this is correlated to the noise in the fog. Perhaps if this is normal, an option could be checked that converts texture lights to simple lights in fog calculations? I've been having to do this manually which is incredibly confusing to keep track of especially when you have lots of different lights; many of which are animated.