Hi, I have spent way too much time trying to get this to work. I want to get motionblur working on an exported flip mesh as alembic in maya arnold 2025. I've tried the velocity on @Cd trick then in maya changing motion vector to Cd, also tried velocityVP, vel, velocity, nothing seems to work. If someone could tell me how to do it I would forever be greatful. But not just say it, would be great to show that it works since I've read every resource available, even exhausted AI for the answers.

Thanks,
Joel

Your best bet so everything works correctly is either loading the data as .ass in Maya or better use the graph Bifrost. Which you can read any attribute without promoting. I can create an example later.

sepu
Your best bet so everything works correctly is either loading the data as .ass in Maya or better use the graph Bifrost. Which you can read any attribute without promoting. I can create an example later.

That would be great to see an example, the bifrost method would be beneficial since I don't have arnold for houdini which I presume you'd need to export an .ass file. Thanks for replying

@sepu any luck? I tried to do it in bifrost but couldn't get it working, though I'm not skilled in bifrost so maybe I missed something.

Sorry just busy I did a quick video here showing the process.
I just grabbed the shelf crown preset and I save a few frames as an .abc load them in Bifrost and as you can see v@v gets converted to point_velocity automatically. You can either save the point cloud in Houdini as an .abc or .vdb points and load it and you could do the meshing inside BF for more control so there is not back and forth or bring the meshing directly as well up to you.
You can also manipulate any attribute btw, like completely override it or multiply, add, etc

Some attributes that you might find useful are

f@pscale = point_size
p@orient = point_orientation
v@v = point_velocity
v@scale = point_scale

And there is more as well but that should get you going. Let me know if you have more questions.



https://streamable.com/vgod9d [streamable.com]

That's actually quite amazing, really appreciate you sharing this workflow. Interesting how we can leave the velocity on the points. Can't thank you enough.

No problem - For some reason the video does not show up - but the link its there as well

https://streamable.com/vgod9d [streamable.com]

I downloaded it earlier, but thanks for sharing the link as well. I'll test it out more tomorrow, but for some reason the cached mesh disappeared in the render, but the points workflow rendered perfect. I'll try tweak some settings to see why the mesh alembic wasn't rendering. Lastly, since I'm not experienced with bifrost I'm no doubt doing something wrong in terms of the aistandard shader, I tried playing with the colour in the attribute editor but it stayed grey. Is there a trick to working with shaders in bifrost?

you either can use the standard_surface inside the graph (for more basic stuff) or if you have a complex network you need to drag and drop the the material from the hypershade inside the graph and use an assign material node in BF, if you want to use an attribute for color, etc use the userdata nodes for that.