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USD export options, Bumps, Normals, Displacements and Arnold shape attributes

Message 1 of 4
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USD export options, Bumps, Normals, Displacements and Arnold shape attributes

I've been testing passing a whole project to Katana through the USD export plugin. Only to find there are plenty of attributes that don't get exported correctly or at all.


- Geometry attributes, catclack and iterations get ignored. There's a @"subdivision method" flag at the export window, which applies a catclark iteration of 1 to everything. Not good.

- If you only connect a single channel to a shader attribute, it gets ignore (typical use case, connect only the "r" channel to a transmission weight, or what have you - there's a workaround for this, which is to use the aiRgbaToFloat though).

- aiBump2d does not work at all? Issue with normals? Can't make it work at all.

- aiNormalMap attributes "color to signed" and "tangent space" won't get exported, and are ignored as defaults. Hence not getting the input from those options and no way to activate it.

I'm VERY eager to hear from anyone who got any of those exporting correctly, any input would be much appreciated.

Thanks for reading.

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Message 2 of 4

Hi Jonathan, I assume you are talking about the maya USD export. Indeed there are currently several major limitations, and nodes / attributes that won't get exported. No arnold geometry attribute is currently supported, and the current system to export arnold shaders is very basic and has a few limitations as the ones you're describing here.

Currently, the best way to get the arnold data exported properly is to use the "Arnold USD" export (in the Arnold menu). I know this export also has its own limitations (e.g. it exports a single frame per usd file), but that's still the best way so far. We are currently working hard with the maya-usd team, so that these 2 exports converge to a single thing with the best of both worlds.


Message 3 of 4
in reply to: JWRodegher

Hi @Sebastien Blaineau-Ortega, thanks for the input.

I appreciate knowing that I shouldn't expect it to work at least.

Oh and yeah, I was referring to Maya's USD export plugin. I have written this exact same post in the plugin's github as well.



Message 4 of 4
in reply to: JWRodegher

I just started trying out USD in Maya, and came to this conclusion myself by experimentation ie that USD basically does not work, lol, to do the most basic thing I would have expected it to do, which is to translate the shading setups from one package to another that are using the same renderer.

While it is great that the Arnold usd export works WITHIN MAYA ie to and from using that kludgy "extra" Arnold specific usd export, what's holdup on the Autodesk side of things?

Will's recent Autodesk "opensource" talks on YouTube are inspiring and great, but where is the follow through? Pixar put USD out there working by 2017, and now we are on Maya 2022.

I'm a keen musician as well as a 3d computer artist, and in the music software industry, we have seen how the transition to Mac ARM native software has gone in that industry - currently ONLY software with licenses that is sold outright have updated their code to run natively, ALL the companies with subscription sales models have NOT yet released native versions of their software, and this includes the biggest names in the industry.

Emulation is not a good way to go in the music industry, as latency means while the code works, it is useless in practice. 3d software has similar extremely taxing requirements on hardware, and emulation is not really an option, and we are seeing Autodesk behaving like the big names in the audio industry with subscription models - VERY SLOW DEVELOPMENT TIMES for crucial updates.

The most common file translation issue that I face in my work is moving assets that are set up in 3ds Max for Vray, and moving them into Maya, generally for rendering in Arnold, although I've been experimenting on and off with other renderers, and I used to use Mentalray.

FBX, Autodesk's inhouse developed supposedly "standard" file format, does not support the export of Arnold or Vray (or Mentalray) assets with their shading intact, and its export of 3ds Max standard materials to Maya with even things as simple as texture placement is spotty and patchy in practice too.

You guys at Arnold seem to be moving ahead of the Autodesk/Maya/3dsMax development teams by implementing this usd kludge in your own software, but what's current the story on the 3ds Max to Maya side things? What's the holdup?

(PS I've been waiting for a standard file format in 3d to appear for around thirty years. so I am not holding my breath for one to appear, but I am greatly encouraged by usd, and hopefully this note will underline its utility beyond its ability to deal with very large datasets, which is also greatly appreciated, in Maya especially.)

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