Nanite clusters constantly paging in and out for nearby objects

Development Rendering
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1

We have a large scene full of Nanite meshes, and clusters seem to page in and out constantly, with even clusters extremely close to the camera being replaced with low resolution clusters.

Initially, I attempted to resolve this by changing the CVar in DefaultEngine.ini in the [/Script/Engine.RendererSettings] settings:

r.Nanite.Streaming.StreamingPoolSize=1024

This did work initially, and continued to work on my machine, but eventually after playing for some time, the issue returned. It’s not feasible to increase this value any further, and we are looking for what sort of settings can be tweaked in order to prevent this cluster paging in and out issue. What sort of information about the scene do we need to provide in order for enough information to be known about the cause?

This issue occurs in PIE Client and Cooked Client. I will shortly upload some screenshots of Nanite streaming info.

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2

Hello,

Thank you for reaching out.

I’ve been assigned this issue, and we will be looking into this Nanite streaming behavior for you.

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3

Hello,

Here is other relevant tickets that contains some information about the Nanite memory pools and their usage:

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Based on your Nanite Streaming stats, we have a couple of follow-up questions, to better understand your setup:

  1. When the camera is still, does the stat “Page Requests” → “New” drop to 0, or does it stay above? If it stays above, what is the average range it stays at?
  2. Have you tried adjusting the following CVars?
    1. r.Nanite.Streaming.NumInitialRootPages
    2. r.Nanite.MaxCandidateClusters
    3. r.Nanite.MaxVisibleClusters
    4. r.Nanite.MaxPixelsPerEdge
  3. Have you audited your Nanite meshes to ensure the correct vertex-to-triangle ratio? The ratio should be less than 2:1, and 1:1 is ideal.

An incorrect ratio can cause inefficient clustering, leading to more triangles being used to draw the mesh than is needed, and thus more content streamed in.

Incorrect rations can be caused by unwelded verts, faceted geometry, or too many UV islands. For more information, please see this documentation:

https://dev.epicgames.com/documentation/en\-us/unreal\-engine/working\-with\-naniteenabled\-content\#facetedandhard\-edgenormals

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