Arnold USD Toonline StandIn Rendering Issue

[scott.wilsonVSATQ]

Hey! My studio has ran into an issue where toon lines do not render correctly with Arnold USD caches. Here's our setup:

1. Create a material with a layer shader to turn on and off the toon lines (some render layers need them off, some need them on).
2. Apply it to geometry, and cache that geometry as Arnold USD (using default settings).
3. Create an Arnold Stand In, insert the cache, and override the layer shader so it renders the toon lines (example shader in zip: test_aiLayerShader1).
4. Set up the render layers and render

ASS Standin Toonline Render

USD Standin Toonline Render

The above examples show that the ASS caches will render the toon lines as expected, but it looks like the USD caches don't know which toon lines to attach to, and picks one at more or less random (I'm assuming it is based on the last added?). We tested on Maya 2020.2 for Linux (CentOS 7) with mtoa 4.2.2, and Maya 2022.2 for Linux (CentOS 7) with mtoa 4.2.4.

Sample files: for_arnold.zip

The zip contains:

• The scene used to make the caches (simpleshapes_aitoon_layershader_cleaned.ma)
• The caches (export.0001.ass and export.0001.usd)
• The scenes used to render the above screenshots (proxy_ass_for_arnold.ma and proxy_usd_for_arnold.ma)

[Stephen.Blair]

Hi @Scott

Thanks for the repro files, I've downloaded them and I'll take a look.
I'm on the east coast (Montreal), so while I may start tonight, I'll probably finish looking into them tomorrow morning.

[Stephen.Blair]

The exported usd is not the same as the exported ass file.

Looks like the usd export doesn't handle the render setup overrides. See the difference?

In the usd file, the toon layer is not enabled (and it's that layer Enable that has an override on it).

[scott.wilsonVSATQ]

Thanks for the reply! So, just to make sure I've wrapped my head around this, does this mean that the USD file doesn't support the render setup overrides while the ASS file does? Or did I miss enabling it?

Also, for the screenshot, I assume ASS on left, USD on right?

[Stephen.Blair]

The USD exporter does not respect the Render Setup overrides, it seems to ignore them (or maybe it always exports the master layer?).

It's USD on the left, and ASS on the right. In the USD, we have:

bool inputs:enable2 = 0

That means the toon layer is disabled.

I think if the master layer has the settings you want to reuse, and that is the active layer when you export, then ass and usd would be the same.