Splotches GI on displacementmod

[Jeroen Prins]

Hi,
I'm using a displacementmod (gradientramp) 2D mapping on a plane.
When rendering i'm getting a lot of splotches in the GI channel.

I use Irradencemap / LC

I noticed i haven't got this problem with bruteforce.
So i'm wondering if its something to do with the settings or with displacement?

Original render is 4000x1810

[Svetlozar Draganov]

Does the displaced plane has volume?
Can you show us also the settings of the VrayDisplacementMod?
Try to increase the Secondary Bias Rays to 0.1 for example.
Run two more test renders - one with only IM activated and another with LC only.