UE Crash when Material Export to Omniverse

Omniverse General Discussion
1

Hello,
I exported an UE Material with the “Export to Omniverse” function. The material shows in the Omniverse Viewer as a MDL.

  1. Once the material is applied to the geometry in omniverse, Unreal Engine states “Distilling” and crashes.
  2. Futher the UV settings from UE are not exported back to Omniverse, though both softwares are in live mode and e.g. geometry transformations are linked back to omniverse.

Below the Crash Log from UE

Thanks. Matthias

LoginId:63d079b84ac2c9ea80b765aaf0db4bb0
EpicAccountId:e460c22fdf364db28e079f9f7212e10a

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff

UE4Editor_AssetTools
UE4Editor_AssetTools
UE4Editor_MDL!FMDLMaterialImporter::LoadTexture() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\MDL\Source\MDL\Private\MDLMaterialImporter.cpp:1087]
UE4Editor_MDL!FMDLMaterialImporter::LoadTexture() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\MDL\Source\MDL\Private\MDLMaterialImporter.cpp:1071]
UE4Editor_MDL!FMDLMaterialImporter::ImportParameter() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\MDL\Source\MDL\Private\MDLMaterialImporter.cpp:2861]
UE4Editor_MDL!FMDLMaterialImporter::ImportParameters() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\MDL\Source\MDL\Private\MDLMaterialImporter.cpp:2954]
UE4Editor_MDL!FMDLMaterialImporter::ImportDistilledMaterial() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\MDL\Source\MDL\Private\MDLMaterialImporter.cpp:787]
UE4Editor_OmniverseRuntime!UOmniverseMDL::LoadMDL() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\Omniverse\Source\OmniverseRuntime\Private\OmniverseMDL.cpp:667]
UE4Editor_OmniverseRuntime!UOmniverseMDL::OnRead() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\Omniverse\Source\OmniverseRuntime\Private\OmniverseMDL.cpp:780]
UE4Editor_OmniverseRuntime!UOmniverseAsset::OmniReadCallback() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\Omniverse\Source\OmniverseRuntime\Private\OmniverseAsset.cpp:389]
UE4Editor_OmniverseRuntime!TBaseUObjectMethodDelegateInstance<0,UOmniverseAsset,void __cdecl(FOmniverseReadResult const &),FDefaultDelegateUserPolicy>::ExecuteIfSafe() [D:\w\9599f8731396a56f\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:611]
UE4Editor_OmniverseRuntime!<lambda_e8d159d5351e879c6dfb1284baa481de>::operator()() [D:\w\9599f8731396a56f\Engine\Plugins\Editor\NVIDIA\Omniverse\Source\OmniverseRuntime\Private\OmniverseConnectionHelper.cpp:744]
UE4Editor_OmniverseRuntime!TBaseFunctorDelegateInstance<void __cdecl(void),FDefaultDelegateUserPolicy,<lambda_e8d159d5351e879c6dfb1284baa481de> >::ExecuteIfSafe() [D:\w\9599f8731396a56f\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:838]
UE4Editor
UE4Editor
UE4Editor
UE4Editor
UE4Editor
UE4Editor
kernel32
ntdll

2

Thank you for reporting this issue. As I look at it and quickly try to repro with a material that I have, I don’t crash. Here are my steps, trying to be a bit more specific so we can narrow down what you’re doing differently:

  1. Right click on UE4 material (not material instance) and select “Export to Omniverse”
  2. Choose a location on my localhost Nucleus server and export with default settings
  3. Once complete, browse to that location in the UE4 Content Browser
  4. See the MDL asset in the Content Browser, right click on it and the MDL begins it translation to UE4 material - textures are saved and created, MDL asset turns into a UE4 matieral asset

It’s possible that your UE4 material has some functions in it that cause our importer or exporter to malfunction. If your steps match mine, then I’m inclined to think that might be the case. Would you be willing to migrate your UE4 material out and share it with us to try to create a repro?

As for the UV Settings, are you just saying that they are hidden and not visible in Create or View? If this is the case, then if you export a UE4 Material INSTANCE where the UV settings are exposed as variables, then you can adjust them. I’m not clear on exactly what your issues is.

3

Update to 4.26 and you should get better results. I was crashing all the time in 4.25.