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USD extract and point cloud

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USD extract and point cloud

Unread postby westrup » Tue Mar 12, 2019 2:20 pm

Hi, i am currently having some problems with USD files between Houdini and Clarisse 4.0. I have two questions regarding USD files in Clarisse.

1. Extract property (attached image) -- It seems like i cannot get Clarisse to corretly read the attributes exported in USD files from Houdini when i use the extract property node. I have connected the extract property node into a switch with luminance as selector. Extract property reads a float attribute "texture" with random values from 0 - 1, but it only chooses the first texture which means all is multiplied by 0 i guess, and therefore not reading the attribute from the file correctly. Same goes with written color attributes. It only shows black if i input it in front color.
I can choose the properties from the dropdown menu inside the node, so Clarisse definitely knows its there but all the values seems to be read as 0. If i import my written USD file in Houdini it can read the attributtes just fine, so it is probably not the file itself thats the problem.

2. Point cloud scattering -- Inside the scatterer i cannot set an USD file as support geometry as you guys do with alembic in one of your tutorials. The USD file is made from a particle sim in Houdini. What are the steps to use a USD point cloud inside of Clarisse as an scatterer?

Plain geometry Clarisse is reading fine with shading groups though, so thats nice :)

thank you
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Re: USD extract and point cloud

Unread postby anemoff » Tue Mar 12, 2019 5:25 pm


1. Can you run Clarisse with the following command line:
Code: Select all
<install_path>/clarisse.exe -flavor ifx -log_level Debug5

This will enable debug logs. If there are unsupported properties, USD will log these in the debug logs.
If possible, can you upload your asset and project files?

2. To use an USD point cloud as Geometry Support in a Scatterer, you must reference it with File > Reference > File, and then select the USD point cloud geometry inside the Reference Context. Geometry bundles can't be used as support as they don't support point clouds. The same rules apply for Alembic.

I hope this helps.
Anthony Nemoff
R&D Engineer
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Re: USD extract and point cloud

Unread postby westrup » Tue Mar 12, 2019 11:58 pm

Thanks for reply.

1. I tried running it with the cmd, but nothing reported. After i tried loading the USD again, and Clarisse did not read the properties from the USD file. They were only in the dropdown menu in "extract property" node because i manually wrote them. I do not see them in the "property editor" window either (not sure if they are supposed to show there). After a lot of fiddeling and hair pulling I managed to get pixar's USDview up and running to see if the properties were properly written to the USD. And they are, as shown in the attached image. For some reason i cannot get Clarisse to see the properties. I do not know if it matters that the properties are written as point, vertex or primitive attributes from Houdini, or if Clarisse should be able to read them all.

I have attached the USD file that is shown in the USDviewer. The attributes that should be read is "texture" and "displayColor". Had to zip the USD, it would not let me uploade the USD extension.

2. Thanks. The problem is solved then. It worked :)
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Re: USD extract and point cloud

Unread postby dcourtois » Wed Mar 13, 2019 10:55 am

Hi Nikolaj,

Thanks for the asset ! It's a bug in our implementation. I've fixed it so it should work fine in the next SP (I can't give you an ETA though :p)
In the meantime, you can work around the bug by:
1. renaming displayColor into something else (those properties are currently ignored)
2. renaming texture into something longer such as "textureIntensity"

Sorry for the inconvenience ! Let me know if the workarounds work :)
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Re: USD extract and point cloud

Unread postby westrup » Wed Mar 13, 2019 2:23 pm

The renaming and extending the property names worked :) Looking forward to the next SP then.
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