H16 Alembic export best practices

[jimmay]

Hi all,

I'd like to pick the brains of the TD's out there on exporting RBD dynamic sims out to Alembic, for their experience with the best settings and practices to use.

In my limited experience so far, I've found H16's Alembic exporter to be EXTREMELY crashy (build 557).  Googling around, however, I don't see hardly any similar complaints, so it means it's probably something I'm doing.

The one common thread I can identify is that of the two sims I've had this issue with, both are based on Steven Knipping's Rigids III tutorial, in which there's an extra stage using Point Deform to simulate dented metal.  One of them is the actual helicopter crash from that tutorial that I built in Apprentice, exported as .bgeo to a commercial Houdini license for testing - the other is an all-commercial scene of a spaceship exploding.

So what suggestions would you have to try and get around this?  Scrub attributes? Clean/normal/facet right before the export?

The only thing that I've seen work so far was to export an unpacked version of the spaceship to Maya - huge, but it got the shot done.  I'm really concerned that something as simple as that helicopter tutorial should be so reliably crashy, though. 

 

[Atom]

You could try exporting the entire simulation out as a .bgeo.sc sequence. Then drop down a File node and bring the .bgeo.sc sequence back in. Then export that File node as your Alembic. This way you could identify if the crashing is related to the simulation or just the export function.

[jimmay]

Hi Atom,

That's what I did with the helicopter scene. The original scene is in Apprentice on my personal laptop, so I exported .bgeo.sc to try exporting Alembic from the commercial install on my desktop at work.  The spaceship shot was done and tried in Commercial from the beginning.

I tried a direct export  File --> ROP Alembic node, and also tried inserting an Attribute Delete in between to wipe out all but the most basic attributes prior to export, and a Facet node to see if the normals had anything to do with it - no difference.  It blows up after writing out 7 megabytes.

Edited April 29, 2017 by jimmay

[Atom]

Have you tried dropping down an Alembic node inside the /out context? From there you can specify the most number of export parameters. Play around with the hierarchy and partition modes...

[jimmay]

Hi Atom,

Yes, that was the first context in which this problem cropped up, as a matter of fact.  Using the ROP Alembic node was an attempted workaround at the suggestion of an experienced colleague who was trying to help me out when this issue was threatening to blow a deadline.  I'm pretty sure it's the same underlying code anyway.

If I have time this week, I might try one of the daily builds, and perhaps ask support if they'd like to take a look. 

 

[sorrowriser]

Hi Jimmay,

I have experienced the same issue while i tried to export a rigid body sim with lots of Lego pieces. Whenever i click export as a alembic file, houdini crashed. My sim was cached and like Atom mention, it was loaded into a fresh scene.

I solved it by deleting all the attributes (v, name, Cd, Shop_material etc. just leaving P,N and uv) and then reCached it. Without caching it keeped crashing. Not sure if its going to workout for you but worth to try.