The leaves of the plant model are twinkling

Development Rendering
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EngineVersion:UE5.4.4

MasterShaderSetting:Masked,TwoSideFoliage

RenderSetting LumenGI,Virtual shadow map，Hardware ray tracingOn/Off

MeshSetting:NaniteAndLOD,This situation will occur in all cases

Under these Settings, the shadows of plant leaves will flash rapidly. This is a scene that looks spine-chilling. Should I use other assets or modify some Settings or command parameters?

Thank you all for your responses.

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This is a common 5.4 combination (Nanite + masked Two Sided Foliage + Virtual Shadow Maps), not a bad plant mesh. The flash is usually the shadow cache or TSR on thin masked cards. Split it with three tests before swapping assets.

  1. Shading model. Duplicate the material and switch it from Two Sided Foliage to Default Lit, still Masked and two sided. If the sparkle stops, it is the foliage shading model (subsurface on sub-pixel leaves) rather than the mesh. On the original, also raise Opacity Mask Clip Value toward about 0.4–0.5 so the mask edge is less noisy.

  2. Virtual shadow invalidation. Thin masked leaves recache VSM pages every frame, especially if the material has any World Position Offset (wind). Disconnect WPO and play once. If the flash stops, put WPO back and set the material’s World Position Offset Disable Distance (a few thousand units) so distant cards stop moving the shadow. On the directional light, turn Contact Shadow off — contact shadows shimmer on leaf cards. Then try:
    r.Shadow.Virtual.ResolutionLodBiasDirectional -1
    Hardware ray tracing on or off will not change this path. Also make sure masked Nanite is actually drawing into the shadow (r.Nanite.ProgrammableRaster.Shadows 1). If that cvar was 0, masked shadows are unstable.

  3. Anti-aliasing. TSR on sub-pixel leaves looks like twinkling even when the shadow is stable. Set the viewport anti-aliasing to None or FXAA for one test. If the flash disappears only then, it is TSR, not Lumen — keep the foliage cards a bit larger or the mask less sparse instead of chasing GI settings.

On the static mesh Nanite settings, turn on Preserve Area so leaf cards do not drop out between LODs. That pop reads as a flash even if you already tried “with and without LOD”.

Whichever single test stops it is the one to keep. You should not need a different asset.