abcStitcher not working for certain files

[Andre Anjos]

Hi all,

We are encountering an issue when using Houdini's abcStitcher where it ends the process before reaching the end of the hierarchy when including specific alembics.
I'm still trying to understand what is doing in the background, but looking into the alembic information, there's nothing I can immediately see being a problem.

In terms of workflow the Alembics are initially exported from Maya, then the abcstitcher in Houdini will run for specific groups of alembics files we need and export them into one alembic to be loaded back to Maya.

Most of the alembics stitch fine, in this case the  `RX01_0024_02.abc` fails to stitch to all our other ones in the group.

It feels like /C_mouth_lower_MESH and /C_mouth_lower_MESH/C_mouth_lower_MESHShape are the culprits.

As versions go:
abcStitcher: 1.8.3
abcEcho: 1.8.3
Houdini: 20.5.370
Maya Exporter: Maya 2024 AbcExport v1.0 1.8.3

The command are we running is:
C:\Program Files\Side Effects Software\Houdini 20.5.332\bin\abcstitcher -v out.abc RX01_0024_02.abc RX01_0024_03.abc

I've also attached the information from abcEcho for both the alembics we want to stitch.

We are stuck at the moment with this, so any help would be much apprevciated.

Many thanks,

Andre

[Lucas Miller]

Based on your AbcEcho output I don't see any obvious problems.

I wonder if the stitching WOULD work correctly on a different OS.

If you have an example that you can safely and privately share with me (and isnt TOO large!), I can try stitching them together with the latest Alembic on both Windows and report back.

Lucas

[Andre Anjos]

Hi Lucas,

 

Many thanks for coming back to me!

 

I’m off for a couple of days and will pm you as soon as I’m back.

Andre

 

Andre Anjos          Pipeline TD       www.realtimeuk.com 0161 711 0260 Call me on teams

     
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From: alembic-d...@googlegroups.com <alembic-d...@googlegroups.com> On Behalf Of Lucas Miller
Sent: 19 October 2024 02:19
To: alembic-discussion <alembic-d...@googlegroups.com>
Subject: [alembic-discussion] Re: abcStitcher not working for certain files

 

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[Andre Anjos]

Hi all,

We might have found the culprit (not sure how I didn't see this in the first instance), but it seems the following ScalarProperty is incorrect and should match the other files.

Object name=/C_mouth_lower_MESH
  CompoundProperty name=.xform;schema=AbcGeom_Xform_v3
    ScalarProperty name=.inherits;interpretation=;datatype=bool_t;arraysize=1;numsamps=97
    ScalarProperty name=.ops;interpretation=;datatype=uint8_t[5];arraysize=5;numsamps=97
    ScalarProperty name=.vals;interpretation=;datatype=float64_t[9];arraysize=9;numsamps=97

I'm expecting when I export the Alembic from Maya it returns an array of 9 .ops and 21 .vals. I can't seem to have this exported from Maya correctly even when baked into a new file.
Is there a way of accessing these properties and make changes?

Many thanks,

Andre

[Lucas Miller]

Ohhhh, this sort of sounds like you've got one one xform topology on one frame, but a different one on the next frame?

Are you animating the values on the xform in a strange manual way without plugs?

Lucas

[Andre Anjos]

Hi Lucas,

You are right! We bake the xforms so we can disconnect the transOPs from the alembic node, which I assume when exporting create new plugs to have consistent number of transOps. The original alembics come with an inconsistent number of transOPs which creates a problem when loading them into our rigs. So our idea was to correct this and publish in Maya.
After the publish they still export incorrectly as assume that when creating a new Alembic Node would fix this, but seems that's not the case.

BTW, I haven't forgotten about sending you some files, but waiting on production to give me a shout.

Many thanks,

Andre

[Lucas Miller]

I probably don't need the example files anymore if you are getting an inconsistent number of ops on some transforms.

One "easy" way to  make the original transforms consistent across all the frames is to calculate a single 4x4 per frame and just rewrite your xform with that single op.

Lucas

[Andre Anjos]

Hi Lucas,

Many thanks for helping us and sorry for the slow reply.

That makes sense and will give it a try.

Andre