Houdini Alembic SOP ignoring higher level attributes?

[Steven Shapiro]

We set up a simple test in Maya where the hierarchy for a cube was:
/group_top/group_mid/pCube/pCubeShape

We added a couple integer attributes to the top and mid level groups.
These wrote appropriately to the resulting abc file (see the abcecho
results at the bottom). However, when imported into Houdini, the
attributes were completely lost. I'm hoping this is a bug and not
intentional. I would think that it would bake the attribute down to
the shape or store the data in some way.

==============================

AbcEcho for Alembic 1.0.3 (built Nov 16 2011 11:53:45)
file written by: Maya 2011 x64 AbcExport v1.0
using Alembic : Alembic 1.0.3 (built Nov 16 2011 11:53:45)
written on : Mon Jan 23 14:54:25 2012
user description : Exported from: /tmp/abcTestCube.ma

ScalarProperty
name=statistics;interpretation=;datatype=string;numsamps=1
ScalarProperty
name=1.samples;interpretation=;datatype=uint32_t;numsamps=1
ScalarProperty
name=.childBnds;interpretation=box;datatype=float64_t[6];numsamps=5
Object name=/group_top
CompoundProperty name=.xform;schema=AbcGeom_Xform_v3
CompoundProperty name=.arbGeomParams;schema=
ArrayProperty
name=dd_testAttr;interpretation=;datatype=int32_t;numsamps=1
ArrayProperty
name=.animChans;interpretation=;datatype=uint32_t;numsamps=0
ScalarProperty
name=.inherits;interpretation=;datatype=bool_t;numsamps=0
Object name=/group_top/group_mid
CompoundProperty name=.xform;schema=AbcGeom_Xform_v3
CompoundProperty name=.arbGeomParams;schema=
ArrayProperty
name=dd_testAttrMid;interpretation=;datatype=int32_t;numsamps=1
ArrayProperty
name=.animChans;interpretation=;datatype=uint32_t;numsamps=0
ScalarProperty
name=.inherits;interpretation=;datatype=bool_t;numsamps=0
Object name=/group_top/group_mid/pCube
CompoundProperty name=.xform;schema=AbcGeom_Xform_v3
ArrayProperty
name=.animChans;interpretation=;datatype=uint32_t;numsamps=0
ScalarProperty
name=.inherits;interpretation=;datatype=bool_t;numsamps=0
Object name=/group_top/group_mid/pCube/pCubeShape
CompoundProperty name=.geom;schema=AbcGeom_PolyMesh_v1
ScalarProperty
name=.selfBnds;interpretation=box;datatype=float64_t[6];numsamps=1
ArrayProperty
name=.faceIndices;interpretation=;datatype=int32_t;numsamps=1
ArrayProperty
name=P;interpretation=point;datatype=float32_t[3];numsamps=1
ArrayProperty
name=N;interpretation=normal;datatype=float32_t[3];numsamps=1
ArrayProperty
name=.faceCounts;interpretation=;datatype=int32_t;numsamps=1

[Steve LaVietes]

It's more of a missing feature than a bug or intentional omission.

There are two ways to load an alembic hierarchy:
1) Single SOP
2) Alembic_archive, alembic_xform and a SOP per shape

For the single SOP case (where transform is baked into the leaf nodes
but not represented otherwise), it'd be possible to apply the
inherited attributes to the primitives.

When the hierarchy is built with alembic_xform nodes and the SOPs are
created for individual shapes, would the expectation be that those
attributes be present on the alembic_xform node or within the SOP in
the same manner?

-stevel

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[Steven Shapiro]

Sorry Steve, I should have been more specific. I'm referring to the
Single SOP case and think it should apply the inherited attributes to
the primitives.

As far as the 2nd method of loading (which we're not planning on
primarily using), I think you would want the option to either apply it
to the xform or on the SOP per shape.

Any guess if this is something that can be included in the 1.0.5
release?

-Steve

[yun-p...@disneyanimation.com]

Hi:
    I recently started looking into 1.5.
I haven't been able to import attributes into Houdini from files exported from Maya.
To clarify, I mean attributes added by users, showing under "Extra Attributes" on Maya's shape nodes.

Is this generally supported?
Any comments are appreciated.

Thanks.

[Lucas Miller]

AbcExport doesn't export these attrs automatically you have to provide the arguments to the command to do so.

[Yun-po Fan]

Thanks, Lucas.

I did, with multiple "-userAttr"s.  And I could bring them back into Maya (AbcImport) and see those attributes.

Bringing into Houdini, however, I'm not able to get any of those attributes.

For experiment, with an Alembic SOP, I can import alembic files exported out of Houdini and see most attributes.  Using the same parameter settings on that Alembic SOP, importing files out of Maya doesn't get me attributes.

Does it work for you?

On Thu, Jul 2, 2015 at 4:48 PM, Lucas Miller <miller...@gmail.com> wrote:

AbcExport doesn't export these attrs automatically you have to provide the arguments to the command to do so.

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[Alex Suter]

I believe Houdini started supporting Alembic user attributes in Houdini 14 and higher. Are you using 13 by any chance?

                        -- Alex

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[Yun-po Fan]

Houdini 14.0, and Maya 2016, by the way.

Thanks.

I also posted another question, Houdini attributes export and import, and it seems I can get attributes out of Houdini and back in Houdini all right, except detail attributes, and array attributes.  Hmm, perhaps I should ask Sidefx too.

[Alex Suter]

SideFX is your best bet. I know they put quite a lot of work into user attributes, but more feedback is always good.

[Yun-po Fan]

Will do (just did. )

Thanks.