Download

Lumen and dense foliage

As illustrated in the image below, Lumen AO on trees with dense foliage gets unnaturally dark.

There are similar issues with DFAO, but those can be somewhat mitigated with the “Min Occlusion” and “Occlusion Tint” settings from the SkyLight. I couldn’t find anything along those lines for Lumen and post process settings alone aren’t enough to work around this issue. Even cranking up the sky light intensity does little to lighten the dark areas.

A setting to control the max occlusion would be useful, especially for more stylized games.

Lumen does not work well with foliage due to how it works off mesh distance fields which don’t take into account the opacity maps for the leaves

To be honest I find it hard to believe Epic would implement yet another global illumination method that doesn’t work with trees…
I mean we had global illumination methods that don’t work well with trees in UE4 already.
Surely there must be a way to finally make this work in UE5?
Hopefully at least by the time UE5 is out of Early Access.

The Hardware Ray Tracing option should work for foliage with Lumen, it would just have a bigger impact on performance.
Ultimately, without doing full ray tracing every fully dynamic lighting system is going to have its downsides because it has to cut corners somewhere

1 Like

I wonder if reducing the occlusion from foliage or masked materials in general would be possible. Either globally or on a per object basis, like a distance field opacity setting.

This gets particularly troublesome with forest scenes, occasionally resulting in complete darkness, as virtually no skylight makes it through the trees. I wonder if a solution is in the works for this, considering the majority of games out there feature some form of vegetation. I guess it explains why we only saw canyon scenes in the demos.

This is huge. How would you go around this? Can i just never use Lumen when I have trees?

You will have to use hardware based Lumen that has higher quality

Lumen foliage is supposedly coming in the full release, hypothetically it could be fine.

There’s other bugs and performance concerns with Lumen anyway so hopefully it will just get better in general.