Hello,
I’m still having issues with vegetation and Lumen in 5.5.
For information:
The trees are fully 3D models, they don’t use any masked materials. Nanite is enabled, as well as Lumen Hardware Ray Tracing.
The problem is that it just looks terrible visually it’s extremely unstable, flickers a lot, and the lighting is very inconsistent. It’s honestly awful.
Here’s a video showing the issue: https://youtu.be/9qmWuJkf280?t=7
I tried increasing r.Lumen.ScreenProbeGather.Temporal.DistanceThreshold, which helps slightly, but honestly the improvement is minimal. It also introduced ghosting on the character in some lighting scenarios, especially when the character is lit by indirect lighting.
I’d like to know if there’s a real solution, or if this is just a limitation of how Lumen works internally. I’ve spent a lot of time tweaking values and testing tons of console commands, but nothing really helps. I really get the feeling that Lumen is just not friendly at all when it comes to rendering vegetation whereas other RTGI algorithms manage it much better.
Would the best option be to disable ray tracing/distance fields on the trees and try some material and SSAO tricks to avoid having them feel too disconnected from the scene?
I saw that 5.6 introduces a proxy system for RT, with a parameter that lets you bias foliage representation in the proxy to reduce AO based on the user’s preference. But honestly, for it to be “stable” (and that’s a stretch it’s still not really stable), you end up with almost nothing left of the tree in the proxy.
Thanks.