Path Tracing vs. Lit Shading: Strand Visual Consistency Issue

Development Rendering
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1

Hi,

This question is from artist.

Path tracing strand visual is totally different from lit shading, which makes artist difficult to use both and maintain visual consistency.

My suggestion is either give up path tracing or make both variant. do you have any suggestion.

Best,

Eason

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2

Hi there,

It is expected to some degree that path tracing will not match lit shading. To better investigate the issue you are seeing please provide a small sample project with the asset and lighting setup you are using for us to investigate.

Please note, Epic Games developers will be unavailable after today until after the Epic Games summery holiday break (June 29 - July 10) and there will be no responses from Epic during this time, though the community may respond to tickets that are not confidential. Upon returning from break we’ll continue to investigate.

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3

Hi,

Thanks for the info. I’ve put together a small sample project that reproduces the issue — please find it attached.

Steps to reproduce:

  1. Open the project and load Content/Map/HairTest.umap.
  2. Switch the viewport to Lit mode comparing to Path Tracing mode.

Sorry for the delayed reply — I’ll follow up sooner going forward.

Let me know if you need anything else once you’re back from break — happy to provide more detail.

Thanks,

Eason [Image Removed]

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4

Hello,

The difference with roughness and albedo are knowns issues and it is also known that the multiscattering look varies a lot. We don’t currently have plans to address these issues and you’ll likely need to maintain different shading logic and parameters using the PathTracingQualitySwitchReplace node.

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5

Hi,

Thank you for the advice. We’ll go ahead and separate the logic using path tracing as suggested.

Best,

Eason

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6

OK, and thank you for providing the examples. While we don’t currently have plans to address this, it helps to have more to test with if our plans change.

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