How to browse an alembic file ? and question about alembic custom "property"

[Hans Baldzuhn]

Hi all,

I have a simple question about alembic file.
I'm currently doing test with alembic to test some features of its
integration in mentalRay.
For this, I export alembic file from maya with abcExport with
different settings. And nothing works ...
I don't know if it could be maya that don't export it the right way or
mental ray that read it the wrong way, and I don't have any way to
know who's wrong. (Even if I strongly suspect the bad integration of
mentalRay in maya that makes new feature not available.)
So I was looking for a way to know what is exactly in my alembic file.
Is there a simple tool that could list all object hierarchy contained
in an alembic file ? With information like polycount, normal, uv, is
it in world space, what is the file frame range, fps, does object have
custom attributes, etc etc. without loading any actual geometry.

And for my problem with mentalRay, I'm not sure about one thing
mentioned in the documentation.
For their alembic implementation, they are talking about " If the
property "material" with a string value is specified on an object"
then it will assign a shader with this name (if it exits in the
current scene) to the object at render time.
I'm not sure about what a "property" is. I asked on the mentalRay
forum and they said it's an alembic term their using for
implementation but they don't know how we can put this inside an
alembic file.
My first thought was that a maya attribute could be this "property"
but it don't seams so. Or it's not working inside maya for mental ray.

Best,
Hans.

[Michel Lerenard]

Hi,

you can use abcecho to get a preview of the data that is in the file. It
will display all the nodes that have been written in the file, with the
number of frames. You won't get detailed information like polygon count
or uvs.
It's not very complicated to output this information, you can easily
modified abcecho to display what you seek.

AbcEcho output with the octopus example file:

AbcEcho for Alembic 1.1.0 (built Sep 3 2012 16:10:03)
file written by: Maya 2012-2.1.SPI x64 AbcExport v1.0
using Alembic : Alembic 1.0.0 (built Aug 5 2011 16:14:46)
written on : Tue Aug 9 13:14:24 2011
user description : Exported from:
/mcp/Alembic_Octopus_Example/alembic_octopus.mb

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=31
Object name=/octopus_low
CompoundProperty name=.xform;schema=AbcGeom_Xform_v3
ArrayProperty
name=.animChans;interpretation=;datatype=uint32_t;numsamps=31
ScalarProperty
name=isNotConstantIdentity;interpretation=;datatype=bool_t;numsamps=1
ScalarProperty
name=.inherits;interpretation=;datatype=bool_t;numsamps=31
ScalarProperty
name=.vals;interpretation=;datatype=float64_t[9];numsamps=31
ScalarProperty
name=.ops;interpretation=;datatype=uint8_t[5];numsamps=31
Object name=/octopus_low/octopus_lowShape
CompoundProperty name=.geom;schema=AbcGeom_PolyMesh_v1
ArrayProperty
name=.faceCounts;interpretation=;datatype=int32_t;numsamps=31
ArrayProperty
name=.faceIndices;interpretation=;datatype=int32_t;numsamps=31
ArrayProperty
name=P;interpretation=point;datatype=float32_t[3];numsamps=31
ScalarProperty
name=.selfBnds;interpretation=box;datatype=float64_t[6];numsamps=31

[Ben Houston]

I recommend using HDFView to browse Alembic files:

http://www.hdfgroup.org/hdf-java-html/hdfview/

It is nicely interactive and looks like the attached screenshot.

Best regards,
-ben

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Best regards,
Ben Houston
CTO, Exocortex Technologies, Inc.
http://www.exocortex.com

[Hans Baldzuhn]

That's great thanks !
I heard about abcEcho a wile ago but I never could find it.
And HDFViewer was exactly what I was looking for !

Hans

>  hdfview.png
> 90KViewDownload

[Ryan Galloway]

I'd recommend using abcview instead of HDFViewer:

http://code.google.com/p/alembic/source/browse/python/examples/abcview

It's a PyQt app that comes with Alembic implemented specifically for
this purpose, as well as an example of how to navigate Alembic
hierarchies using the Alembic Python bindings. It also has a built-in
Python console widget preloaded with the scene context so you can
inspect the Alembic objects further if necessary (just run help() in
the console).

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