Nanite Vegetation with Skeletal Meshes not visible in RT scene

Development Rendering
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1

Hi!

We are seeing an issue with Nanite vegetation with Skeletal Meshes:

  • The mesh is not present in the Ray Tracing scene
  • As a result, it does not affect Lumen lighting, even though the CardPlacement debug shows Lumen is aware of the object and has created cards for it

See attached screenshot.

Things I have checked:

  • Nanite enabled
  • Nanite Foliage enabled
  • r.RayTracing.Geometry.SupportSkeletalMeshes 1
  • “Visble in Ray Tracing” enabled in actor / its SkeletalMesh component
  • “Support Ray Tracing” enabled in the skeletal mesh asset

I have included a minimal repro project.

Am I doing something wrong? If not, are you aware of this and planning to fix it?

skeletal mesh.jpg(347 KB)

2

Steps to Reproduce

  1. New empty project
  2. Import the demo skeletal mesh trees trom the Megascans library
  3. In Project settings: Enable HW raytracing, disable SDF generation, enable nanite Vegetation
  4. Place a tree on an empty map
  5. r.Lumen.Visualize 1
  6. r.Lumen.Visualize.CardPlacement 1
  7. Observe that the tree is not visible in the RT scene in the debug visualization, but its cards are visible in the Cardlacement visualization
3

Hi Lukas,

Have you been able to try setting r. RayTracing.Nanite.Mode=0? Doing that should add the fallback mesh to the BVH, provided you have added one for the tree. You might also see a r.RayTracing.Nanite.Mode=2 for a new mode that allows us to add cluster information to the BVH, but it is still being worked on and should not be used right away. Let me know if that helps.

Cheers,

Tim

4

Hi Tim!

I’ve just tried it, none of the values seem to make any difference.

Cheers,

Lukáš

5

Ok, no problem. That was just as a quick sanity check. I will check out the repro project once I am back in the office and get back to you with some updates by the end of this week

6

Hi again, I found out that this was a known issue that got recently fixed. Can you try a build with CL 54773674 to see if the issue persists?

7

Glad to hear it! I will close out the ticket then. Please don’t hesitate to reach out again if you find any other bugs.

8

Thanks, that changelist fixes the issue!