Landscape has a seam when scale is set to a decimal

Development Programming & Scripting
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This question was created in reference to: [Gaps between landscape subcomponents with non-integer [Content removed]

Hello we are experiencing the same issue.

Do you have any idea where to llok in the code to fix the issue?

This was resolved and then reopen.

https://issues.unrealengine.com/issue/UE\-174155

There is a target fix on 5.8.

If there any change that we can grab to fix the issue on our side?

Thanks

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Hello! I’ve looked into the state of UE-174155. It was temporarily marked as “Can’t repro”, but opened again because we have been able to repro it internally. The bug hasn’t been fixed yet. “Target Fix 5.8” is just indicating that the fix might come with UE 5.8, but the bug hasn’t been addressed yet. It’s also not an indication of priority. I’ll add to the internal info of UE-174155 that you are impacted by the bug.

“Do you have any idea where to llok in the code to fix the issue?”

My colleague has narrowed the issue down to a loss in Scale precision in the shader function DecodeTransform in SceneData.ush. That’s what we know so far.

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Thanks [mention removed]​

We ended up setting this flag `bSupportsSceneDataCompressedTransforms` to false.

It fixed the issues without loosing too much in performance

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Thanks for sharing that! I’ll pass that on internally too. I’ll close this case since you’re unblocked.

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Hi Francois,

Are you guys not using Nanite landscape? It shouldn’t suffer from that precision issue because of the “skirts” polygon strips that are generated on the edges of landscape proxies to cover the potential gaps. If so, then you shouldn’t need to disable compressed transforms, which seems like the nuclear option as it will leave a certain amount of performance off the table across all primitive types, not just landscape.

Cheers,

Jonathan

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Hello [mention removed]​

Thanks for the reply.

We are using Nanite Landscape. Is there something that we miss during our setup?

Thanks

Francois

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No, it’s just that in the editor, Nanite landscape can be not up-to-date, if a change was made to landscape for example. But the Nanite mesh gets recomputed when saving or cooking, so the problem should not be present in the final game (or when Nanite landscape is up-to-date in the editor, which you can verify by clicking on Build/Build Landscape, which updates all the outdated Nanite meshes). Just make sure that Nanite skirts are enabled in the landscape properties but that should be the case by default.

Let me know if you have additional questions,

Cheers!

Jonathan

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