Hey! I'm trying to learn and build an USD set completely textured and modelled but looking at your videos I find it hard to see how the process or texturing and importing individual assets would look, isn't the idea of using USD to make it easier to keep referencing individuals assets to your scene, create variants and keep building a set dressing? Right now you are texturing everything together and everything is exported together too. What if I need to start texturing let's say the couch while my modeler keeps working on the rest of the set? Can't I just export an USD for each asset and then assemble everything in a single scene? I feel like having the assets separated is also important to easily do look dev turnarounds of them. For now I'm trying to figure stuff one by one by I have lots of questions. Thank you for taking the time to do the videos! 😄
Yes. In this video I export out the USD components which are assembled into a USD set. I’m also using USD layers for each department so Modeling can work parallel to lookdev. The lookdev part here uses Arnold materials. In the future we’d instead use MaterialX materials together with USD which would allow other software like Houdini and Unreal. Currently materialX and USD are not fully working in Maya. Hopefully soon.
I think what everyone is doing, is incrementally switching, so as to take advantage of the features in USD without breaking their existing pipelines. So we are not talking about switching, but rather taking baby steps. The question you would need to consider is whether those features of USD would be of advantage to you for your particular use-case,
You've mentioned "instanceable" option for making instances... No matter what I do it doesn't seem possible to apply a material to the instance, it returns an error (# Error: RuntimeError: file line 2: Cannot create prim spec at path ; authoring to an instance proxy is not allowed. RuntimeError: Used null prim.) The only solution seems to be to apply material to the asset BEFORE payloading it in and turning on "instanceable" (in the asset .usda where I payload _geo.usd). So, it seems that using _LOOK.usda scene over the model that has instances doesn't work... or am I doing something wrong?
With the LOOK sublayer targeted, turn off instancing on the component. You can then make any edits (for example assign a material), and turn it back on once you are done. Ideally, you would be doing a material override, but this is not supported in Maya USD currently.
I had initially done this following the pattern of the Pixar Kitchen USD scenes. However, I was left with same question, which I asked on AOUSD: forum.aousd.org/t/understanding-components-with-payloads-in-the-pixar-kitchen/758 The short answer is that in current USD you would not need to have this, and could just payload _geo.usd directly as you said. However, we use sublayers per department (modeling sublayer, lookdev sublayer) which want to be able to mute. Having an intermediate contents layer preserves the ability to mute these layers. Targets of references and payloads are considered root layers and if muted, trigger a composition error. This error is arguably unnecessary and will likely be removed in the future. But until then, I think I'll keep it as is.
Thanks for the tut. There seems to be an issue in df_USD_mtlExport.py line 65 running in Maya 2024.2/MayaUSD 0.25.0 - Usd.Stage.Open() looks for a file, but gets a path without .usd ext in the end and throws an error. layer_to_edit = mtl_file + '.usd' solves the problem.
Loading the file in USD Layer Editor after "sans_mesh" fails though: // Error: Failed verification: ' result == MStatus::kSuccess '... Works fine before "sans_mesh".
Thanks good to know. I'll follow up on that. FYI, USD 0.26 has the option to export materials separately. I have not tried it yet, but sounds promising!
Fix has been pushed to my repo. The solution was to change line 132 to mtl_file = stripExtension + '.mtl.usd' as Maya's file cmd did not like the .usda extension.
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Your channel is a true treasure to me
Thank you
So nice of you to say!
very informative beginner guide, appreciated your work and effort on this Derek !
Glad it was helpful!
Very Informative, thanks a lot!
Glad it was helpful!
Hey! I'm trying to learn and build an USD set completely textured and modelled but looking at your videos I find it hard to see how the process or texturing and importing individual assets would look, isn't the idea of using USD to make it easier to keep referencing individuals assets to your scene, create variants and keep building a set dressing? Right now you are texturing everything together and everything is exported together too. What if I need to start texturing let's say the couch while my modeler keeps working on the rest of the set? Can't I just export an USD for each asset and then assemble everything in a single scene? I feel like having the assets separated is also important to easily do look dev turnarounds of them. For now I'm trying to figure stuff one by one by I have lots of questions. Thank you for taking the time to do the videos! 😄
Yes. In this video I export out the USD components which are assembled into a USD set. I’m also using USD layers for each department so Modeling can work parallel to lookdev.
The lookdev part here uses Arnold materials. In the future we’d instead use MaterialX materials together with USD which would allow other software like Houdini and Unreal. Currently materialX and USD are not fully working in Maya. Hopefully soon.
would USD be worth the switch over if your a "one man Studio" that does everything?
I think what everyone is doing, is incrementally switching, so as to take advantage of the features in USD without breaking their existing pipelines. So we are not talking about switching, but rather taking baby steps. The question you would need to consider is whether those features of USD would be of advantage to you for your particular use-case,
You've mentioned "instanceable" option for making instances... No matter what I do it doesn't seem possible to apply a material to the instance, it returns an error (# Error: RuntimeError: file line 2: Cannot create prim spec at path ; authoring to an instance proxy is not allowed.
RuntimeError: Used null prim.)
The only solution seems to be to apply material to the asset BEFORE payloading it in and turning on "instanceable" (in the asset .usda where I payload _geo.usd). So, it seems that using _LOOK.usda scene over the model that has instances doesn't work... or am I doing something wrong?
With the LOOK sublayer targeted, turn off instancing on the component. You can then make any edits (for example assign a material), and turn it back on once you are done.
Ideally, you would be doing a material override, but this is not supported in Maya USD currently.
Can you, please, explain the purpose of the intermediary _payload.usda file? Why don't we just payload _geo.usd directly into final element .usda?
I had initially done this following the pattern of the Pixar Kitchen USD scenes. However, I was left with same question, which I asked on AOUSD: forum.aousd.org/t/understanding-components-with-payloads-in-the-pixar-kitchen/758
The short answer is that in current USD you would not need to have this, and could just payload _geo.usd directly as you said.
However, we use sublayers per department (modeling sublayer, lookdev sublayer) which want to be able to mute. Having an intermediate contents layer preserves the ability to mute these layers. Targets of references and payloads are considered root layers and if muted, trigger a composition error.
This error is arguably unnecessary and will likely be removed in the future. But until then, I think I'll keep it as is.
Thanks for the tut. There seems to be an issue in df_USD_mtlExport.py line 65 running in Maya 2024.2/MayaUSD 0.25.0 - Usd.Stage.Open() looks for a file, but gets a path without .usd ext in the end and throws an error. layer_to_edit = mtl_file + '.usd' solves the problem.
Loading the file in USD Layer Editor after "sans_mesh" fails though: // Error: Failed verification: ' result == MStatus::kSuccess '... Works fine before "sans_mesh".
Thanks good to know. I'll follow up on that. FYI, USD 0.26 has the option to export materials separately. I have not tried it yet, but sounds promising!
Fix has been pushed to my repo. The solution was to change line 132 to mtl_file = stripExtension + '.mtl.usd' as Maya's file cmd did not like the .usda extension.
How to use same usd in ue5
that would need to be another video