LPV light flickering


I’m having a weird issue with LPV. The light flickers when I get close to anything, assuming what it looks like a skylight color. I did have a skylight in the level, but right now it’s disabled (both by unchecking “Affect World” and unchecking “Visible” on the Rendering category) because I need to have pitch black areas. As you can see in the first gif, the pitch black areas actually work, and the entire level lighting is good for my purposes, but when I get close to anything, bam! it happens. The level is friggin’ huge (no Landscape, though), and the LPV Size is on 200k units. It could be the issue, but the flickering changes colors when I move the light around, which leads me to believe that the Directional Light position could be affecting it as well.

Anyways, I would like to know what could be causing it. I’m not really certain about what could be the cause at this point. Here’s some of the things happening with this:

  • It’s not light bleeding. The tunnel is encased inside 300 units cubes. Also, in the outdoor take, it’s clear it’s not bleeding.
  • LPV Bias is quite high (on 8.0), but changing this setting doesn’t affect the flicker.
  • LPV intensity doesn’t affect the flicker itself. Masks it a bit by making everything brighter, but in areas where the effect is subtler, the flicker is there, on pretty much the same brightness.
  • Changing the LPV size affects the flicker (marginally), but going lower than 200K means parts of my level get lost. Still, the effect it has on the flicker is minimal, and reducing the size introduces other flickers (this time certain light bleeding, and the usual stuff caused by having a smaller volume than the actual geometry).
  • Ray Traced Distance Field Shadows have no effect on flicker. Neither altering Cascade Shadow Maps settings.
  • Post Process Volume has nothing changed except for LPV. Unbound, of course.
  • The flicker color is affected by light angle, as stated before, but it doesn’t affect its brightness.
  • The flicker appears to be distance based. It moves with the camera. Could it be occlusion, or light culling of a sort?
  • It appears on EVERY mesh. This leads me to believe it’s material independent.
  • Changing the Directional Light has no effect. It’s entity independent.

Well… Halp :slight_smile:



So, I answered myself this one. It turns out one of the RenderTargets I was using had too high of an emissive value. Apparently, LPVs take Emissive surfaces into account (well, duh). However, since emissives for RenderTargets aren’t particularly dynamic during lighting tests (what with them being monitors and stuff), their voxelized LPV projection gets in the way.

So, I got rid of them, and now it looks like a charm! :smiley: