Objects partially or completely black on lumen scene

[Ricfm]

Hi, I’ve been working on a scene for an archviz project and I’m facing some issues:

• I’m modeling my scene in maya, exporting fbx and rendering in UE5.1
• I try to make my topology as optimized as possible, i deleted history and froze transformations, unwrapped UVs and checked normals.
• I’ve separated most walls, floors and details
• I have tried using UE skylight, creating my own light system, and using ultra dynamic sky
• I’ve converted my meshes into nanite

No matter what I do there’s always some objects or part of them that are not working with lumen and appear black on lumen scene.
I’m leaving some screenshots from my topology on maya, my lit view mode and my lumen scene.

Thanks in advance for your help!

[Arkiras]

is “Affect Dynamic Indirect Light” enabled for those meshes?

[Ricfm]

Yes, it’s enabled for the whole structure

[Arkiras]

@Ricfm

is this the lumen scene view or the reflection view?

[Ricfm]

it’s the lumen view, but i just realize it look the same in the reflection view

[jblackwell]

What size is the mesh upon import? Did you have to scale it up at all?

[Ricfm]

It was too small, and i scale it up to real size, i exported another version with the correct measures but it keesp happening

[jblackwell]

What happens if you use the console to visualize the lumen mesh card placement (visualize.cardplacement. 1) or something like that?

The first question to determine is if lumen is generating cards at all for some meshes. Lumen supports texture feedback so if you scale up an object the card scales up too, but that only applies to meshes that were big enough to have cards generated for them at all.