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Juri Mejan-Fripp avatar image
Juri Mejan-Fripp asked ·

Acceleration Blur in Maya from Houdini

Hi,


I'm trying to get acceleration motion blur to render with exported alembics from houdini within Maya. I have got the force attribute as a vertex attribute on the alembic cache and have a setup rendering in HtoA working with accceleration motion blur on the exported alembic, however I can't find the method to get this to work within Maya. It only renders velocity motion blur which is linear and ignores substeps within the alembic cache.


I have exported an .ass from houdini of the alembic and rendered that within Maya using an aiStandin and that renders with acceleration motion blur, but this method isn't implemented in our pipeline so not really a good solution.


Is it possible to get acceleration motion blur to render within Maya on an exported Alembic from Houdini, or is this parameter just not supported.


I was hoping there would be a setParameter I could use to specify the vertex attribute to use to set the acceleration blur parameter.

Alembic Render mtoa

Ass Render mtoa


Thanks,

Juri

motion blurmtoa htoa
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Juri Mejan-Fripp avatar image
Juri Mejan-Fripp answered ·

Thanks Ashley,


Is there a way to add this as a feature request for MtoA?

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Ashley Handscomb Retallack avatar image
Ashley Handscomb Retallack answered ·

The Houdini scene unpacks the alembic and generates the acceleration blur as raw polygon data. The "force" attribute is used to generate the samples for the list containing the positions of the points at each sample.

This is currently not the data we use in the alembic procedural so would require an enhancement to the procedural to be able to use acceleration data based on an arbitrary user data (e.g force attribute)






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Juri Mejan-Fripp avatar image
Juri Mejan-Fripp answered ·

Hi Ashley,

Thanks For your response.

I cant upload the files to the forum, file sizes are too large and it doesnt support the extension, I have place them on my google drive here:

https://drive.google.com/drive/folders/1lQpHPu9RMIiiFyPyWB3mYroFQ-hTj5lL?usp=sharing

I looked at the .ass to see if i could get any additional information out of it and all I could fins was the lines to set a varying vector and then the point attributes for that vector.

declare force varying VECTOR

force 75021 1 VECTOR

This didnt help me work out how to use a setParameter to define what vertex attribute defines the Acceleration blur

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Thanks Juri, please note that as your company has Arnold licenses you can contact us directly at support@arnoldrenderer.com

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Ashley Handscomb Retallack avatar image
Ashley Handscomb Retallack answered ·

Are you able to share your maya scene, the exported .ass and the alembic file?

If it works in houdini and from the .ass file then it should work in maya, as they both use the same alembic procedural. HtoA may be setting a parameter differently to MtoA however

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