Vertex Map Motion Blur

[simon_russell]

I'm just trying to use vertex maps (from Houdini) to create motion blur in C4DtoA.

I've followed the guide. Dropped in the vertex maps. Follow all the steps (I think) but can't see any motion blur. I'm sure I'm missing something basic but can't see what. Any help appreciated.

Also, the example file for this is corrupt (says incorrect file structure when loading). From this page. https://support.solidangle.com/display/AFCUG/Motion+Vector+Parameters

Thanks,
Simon

vel-problems.zip

[peter.horvath6V6K3]

You're doing everything fine, there's a problem in the plugin. The Alembic importer creates a special vertex tag which is not recognized by the plugin and so the motion vector is not exported. I'll fix this in the next release. Thanks.

[peter.horvath6V6K3]

Btw, it should work if you specify the maps by name. Only the linking is the problem.

[aaron_barreras]

Quick question, has this issue been fixed yet, as I still can't get vertex maps to work using the Arnold tag?

Like Simon, we've been bringing in sims from Houdini as Alembics and need to get motion blur. For the most part, I've been using Procedural Objects, which so far have been working perfectly. However, we get a lot of scenes already set up from our artists using Alembics, so sometimes it would be more convenient to use the native imports, instead of having to redo all their work as Procedurals.

Sidebar note, it was mentioned that specifying maps by name works, but I've not had luck with that either. Using "v_1", etc, as stated on the help page doesn't appear to do anything with the Houdini Alembics I'm using; is there a specific syntax I might be missing?

Either way, Arnold Procedurals seem to be a more reliable workflow, but I was just curious about vertex maps in case we ever did need to go that route.

[peter.horvath6V6K3]

It was supposed to be fixed in C4DtoA 2.4.1. Can you send me a repro scene please?

[aaron_barreras]

Hello Peter, in playing with this issue a bit more, it seems that the motion vectors do render, but not in the IPR (even with the motion blur button enabled). What's odd is that if you load the exact same Alembic in as a Procedural it renders correctly in the IPR. Maybe it's something I'm doing incorrectly in the setup?

The file is too big to attach, so here's a Dropbox link:

https://www.dropbox.com/s/0jqajjy1djl0a8o/Alembic_motion_blur_issue.zip?dl=0

It's just the default crown splash from Houdini, exported as an Alembic. There are two C4D files; the first one uses the native Alembic import along with motion vectors, and the second file uses the Procedural object.

Any thoughts as to what I might be doing wrong?

[peter.horvath6V6K3]

Ahh, ok, there is a bug and vector motion blur does not render in the IPR. I just fixed this issue this week, will be in the next release. The procedural renders correctly because the motion keys are written properly to the ass file.

[aaron_barreras]

Great to hear, thanks Peter!