artifacts in lumen mode when rendered in 4K

Development Rendering
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1

HI,

I’m experiencing issues with incorrect reflections when rendering in 4K resolution. When I render in Full HD the result is correct. I’ve already tried modifying several parameters but to no avail. Below are the images comparing the results in both resolutions.

Can anyone help me with a solution?

  • The problem only appears in Lumen mode.
  • The problem only appears in 4K resolution
  • Disabling HDR the problem persists.
  • I’ve already changed all the render quality parameters, shadows, camera. Nothing worked.

4K RESOLUTION
4K RESOLUTION1920×1080 196 KB

Full HD Resolution
Full HD Resolution1920×1080 181 KB

2

Its really sad that this issue still exists. We had similiar problems in UE5.1 and I hoped they solved this since then.

You can try:

  • lowering final gather quality in the lumen settings
  • increasing the downsample factor for the final gather
  • lowering your screen percentage

I know that all of these solutions are bad cause you’ll get a lower quality result but we did not find a better way of dealing with this.

Back than we even payed for UDN support but we could not solve this.

3

For high resolution rendering (Resolution / r.Lumen.ScreenProbeGather.DownsampleFactor) * r.Lumen.ScreenProbeGather.TracingOctahedronResolution can exceed max supported texture size and cause such artifacts. Try scaling down r.Lumen.ScreenProbeGather.DownsampleFactor and / or r.Lumen.ScreenProbeGather.TracingOctahedronResolution by a power of two.

And indeed we should fix it. I’ll make a note to fix it for 5.5.

1 Like
4

Tiled rendering solves this 4K resolution problem