white spots in GI when light is to close to wall.

V-Ray V-Ray for 3ds Max Issues
1

Hello.
I’m using several planar vraylights to iluminate a garage.
These lights have decay and are near the ceiling.
The GI methods are Irrmap for 1st bounce and QMC for secondary
When this lights are single sided (pointing down) GI is ok but if they are double sided the GI generates some very bright samples making the result look like is there has a ball of mirros scattering white spots.
I guess this happens because the light hitting the ceiling is very intense due to the fact that I’m using decay.
If I move the lights away from the ceiling white spots disapear.
Is there a way to avoid the white spots in GI but have the overbright effect of intense light hitting the ceilling?
Should I change methods for the GI??
Thanks

Here are some tests with a simple grey vray material:

Single Sided Lights

Double Sided Lights

2

First of all, you can try to use the light cache for secondary bounces. Next, you can try to place a larger VRayLight in “skylight portal” mode a little below or above the other lights. It should be big enough to cover the “overbright” effect on the ceiling.

Best regards,
Vlado