Nanite Tessellation causes discontinuities along UV seams, resulting in visible cracks in the tessellated mesh. This happens only when using (Dynamic) Nanite Tessellation and doesn’t happen in Nanite Static Displacement because the latter is implemented on the CPU and there is a crack filling algorithm in FAdaptiveTessellator.
I understand that this feature is experimental. However I would be interested if you are planning to address the issue or should we find a workaround ourselves. I have tested it on the p4 main branch, but the issue is probably present since the introduction of the feature.
thanks for reaching out. I was able to reproduce the issue on my end and did some investigation into Nanite tessellation. There is an Unreal Fest talk from 2024 which (towards the end of the talk) mentions cracks appearing with Nanite tessellated geometry at this link: https://youtu.be/6igUsOp8FdA?si=cEkSrA99OvkHmAsm&t=2148.
As tessellation is calculated based on the geometry’s normal, cracks will appear when there is a hard edge or UV seam on an asset and are an inherent limitation of tessellation. One way to mitigate the issue is to manually add a bit of extra geometry to smooth out the hard transition.
I hope that helps, but let me know if you have more questions.
thank you for the useful tips on how to manually mitigate the issue. We were hoping for an automatic solution but if I understand correctly from your answer, there are currently no ongoing efforts on your side to mitigate the issue in engine without artist intervention.
I checked the public roadmap and did not find there was a fix for making Nanite tessellated displacement crack-free in the plans. However, I found another potential workaround explained in this video (at 23:49) and involves using a single smoothing group for the asset. Hopefully that can help in your case.