4.5.0
4.2.0
4.1.0
4.0.0
4.5.0
2023.1.1
2023.1.0-hotfix.1
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Operating System
Ubuntu 22.04
Ubuntu 20.04
Windows 11
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GPU Information
Model: RTX 4080 Super
Driver Version: 566.36
Hi everyone!
I exported a few assets from Unreal Engine 5.5 to USD for use with Isaac Sim. However, upon importing i notice that some of the geometries have incorrect surface normals (the reflections look skewed and stretched to one side or another). This happens while opening the usd directly in both Isaac and USD Composer. However, the same usd in blender does not show incorrect normals (both render or in openGL viewport).
What could be the reason for this odd behavior? How may I debug this further?
Any help would be appreciated. Thanks!!
I have tried importing the same usd in blender 3d and that works correctly. I have also tried changing export settings in UE (to not export a normal map or tangents altogether) but to no avail.
I did further debugging, with simpler objects and have found that the issue was not with geometries but with the normal maps and how they render inside of Isaac.
On a much simpler object, just a cube that’s been unwrapped, this is how it looks like:
In the mdl node graph, it is set to raw colorspace. Other applications interpret this normal map correctly, so I am not entirely sure what the difference is here. Does Isaac expect world space normal maps as opposed to tangent space?
@ankit.pruthi i don’t have Isaac Sim in front of me, but could flipping the green channel of the normal map yield anything different? i can see if i can repo this when i get back to my machine. in the meantime, could you share a screenshot of your shader graph?
Hi,
Here’s how the shader graph looks like. I am unable to edit this graph though.
I tried using the normal map above in a completely new shader inside Isaac as well rather than the one created from UE export but that doesn’t fix it either. Nor does flipping V.
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