Landscape Spline Road Merged Into One Static Mesh Doesn’t Use LODs or HLOD in World Partition

Strider
Mon, 03 Nov 2025 19:44:40 +0000
Debugging, Optimization, & Profiling

I created my roads using the Landscape Spline Tool in Unreal Engine 5.5.
Everything worked fine, but the spline generated around 10 000 draw calls and about 100 000 primitives when looking at the whole map.

To optimize, I selected the LandscapeSplineActor and used Merge Actors to turn the entire spline network into one Static Mesh.
After merging, draw calls dropped significantly (≈ 2 500), but now primitives increased to ~1 million, because it’s now one single object that always stays at LOD 0.

World Partition and HLOD are enabled and working correctly for the landscape — the landscape changes LODs (pink/yellow colors in visualization), but the merged road mesh always stays white and never changes its LOD level.

The merged static mesh contains proper LOD levels (LOD0–LOD3) and is Static, with HLOD Layer = Default.
Even after Build HLOD, the road does not use its LODs or appear in HLOD coloration; it always renders at full detail.

So, draw calls decreased (good), but primitives exploded (bad) because the merged road mesh never switches to lower LODs inside World Partition.

I’ve been trying to fix this for days — any tips or experience with this issue would really help me out, thanks!

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