python IPointsSchema missing getArbGeomParams()

[Bob Mercier]

I'm saving a point cloud from Houdini and it includes some arbitrary geometry parameters.  I'm able to read the extra

parameters from C++ using Schema::getArbGeomParams() but that api seems to be missing from the Python

interface.  Is there another way to get at the extra parameters?

thanks!

bob

[Bob Mercier]

Hmm...  Nobody likes python?  Attached is a simple C++ example that shows IPointsSchema does contain getArbGeomParams().

I'm happy to believe it's a build problem, but I'd love for someone to tell me that CAN call getArbGeomParams() from an IPointsSchema object,
or suggest another way.

A related question, I've tried building alembic on a new-ish Linux using the latest python and openexr (imath), as well as the "recommended", i.e.
openexr-1.7.1, python 2.6, and have had about the same results.  Also, I had to fiddle with the link order on one of the CMake scripts to get PyAlembic
to work at all.  Has anyone else had satisfactory results?  Care to share you build recipe?

thanks!
bob

[Bob Mercier]

Ok, here's the "other way":  

 

    if alembic.AbcGeom.IPoints.matches(md):
        pnts = alembic.AbcGeom.IPoints(obj, alembic.Abc.WrapExistingFlag.kWrapExisting)
        schema = pnts.getSchema()
        c_prop = alembic.Abc.ICompoundProperty(pnts.getProperties(), ".geom")
        if c_prop:
            arb = c_prop.getProperty(".arbGeomParams")
            if arb:
                print "HAS ARB"
                m_prop = arb.getProperty("mtx")
                if m_prop:
                    matrices = m_prop.getValue()
                    for mtx in matrices:
                        print mtx

Moving on...

On Saturday, October 18, 2014 9:13:15 AM UTC+8, Bob Mercier wrote:

[Ryan Galloway]

Hey Bob,

Thanks for the report, and apologies for the radio silence. Looks like this might have been an oversight in the Python bindings. I've submitted a fix and a pull request here:

https://github.com/alembic/alembic/pull/12

We may wait a few more days for additional reports from 1.5.6, and then cut a 1.5.7 version. If you need the fix now, you can clone my cask-dev branch and build that.

Alternatively,  you can definitely access properties directly like that as a workaround. For Python tasks, I also encourage you to check out "cask", which makes inspecting caches a lot easier, and also updating and merging archives possible:

http://docs.alembic.io/python/cask.html

Regards,

Ryan

 

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[Kevin Campbell]

Hi All,

i'm currently working with alembic data which is exported from katana and imported into houdini.
For various reasons i don't actually have access to katana itself, but need to manipulate the alembic files.

Using the (otherwise splendid) cask.py from alembic/1.5.5 i have found that reading
the alembic file and then writing it out doesn't perfectly preserve the data.
There are 'visible' properties of type int8 and '.ops' properties
that are not preserved.

The original katana alembic will load into houdini,
the new alembics coming out of cask caused houdini to crash.

In order to get things to work, i needed to change the OPROPERTIES
dictionary in cask, adding in 'visible', imath.Color4c, and changing '.ops'.
A patch is attached.

Unfortunately i cannot supply alembic files that demonstrate the issue,
and i suspect that the change in '.ops' may cause issues for other applications
but the patch may be useful to others.

kevin

--
kevin campbell
director of production technology | kevin.c...@rsp.com.au
rising sun pictures | www.rsp.com.au
phone +61 8 8400 6456 | mobile +61 432 483 166

[Ryan Galloway]

Hi Kevin,

Thanks much for the report and the patch. I'm glad to hear you're getting some use out of cask.

There have been a few important updates since Alembic 1.5.5. The current released version of cask is 0.9.3, but I have an even newer 0.9.4 available in my cask-dev branch here (which, FWIW, is the version we're using at ILM):

https://github.com/rsgalloway/alembic/blob/cask-dev/python/examples/cask/cask.py

This may get released with the next update to Alembic, but in the meantime, please check it out. I think it might solve these issues for you and maybe one or two others you might not have encountered yet:

If it doesn't, or any other issues come up, please let us know.

Ryan

[Kevin Campbell]

----- Original Message -----
>
>
>
>
> Hi Kevin,
>
> Thanks much for the report and the patch. I'm glad to hear you're
> getting some use out of cask.
>
> There have been a few important updates since Alembic 1.5.5. The
> current released version of cask is 0.9.3, but I have an even newer
> 0.9.4 available in my cask-dev branch here (which, FWIW, is the
> version we're using at ILM):
>
> https://github.com/rsgalloway/alembic/blob/cask-dev/python/examples/cask/cask.py
>
> This may get released with the next update to Alembic, but in the
> meantime, please check it out. I think it might solve these issues
> for you and maybe one or two others you might not have encountered
> yet:
>

Hi Ryan,

Yes, this version does deal with our katana/houdini compatibility issue
(somewhat more elegantly than i did, as well).

Thanks,

[Ryan Galloway]

Excellent! Glad to hear it. Please do continue to send us reports, or any feedback you might have.

Thanks,

Ryan