Error reading Alembic: unsuported type

[Pablo Gimenez Pizarro]

Hello.

I was testing some alembics in Gaffer and I found is generating warning because

of the data type used for the Pref attribute in our Maya exports:

WARNING : PrimitiveReader::convertArbGeomParams : GeomParam "Pref" on object "/gen_man_model_grp/body_grp/eyes_teeth_grp/l_eye_grp/l_iris_geo/l_iris_geoShape" has unsupported type

If I do an abcinfo I got this:

Vertex point real64 Pref[3]

And if I try to inspect the attribute in Gaffer in the Primitive Inspector I can't see it.
If I open it in Houdini no probs.
This is with Gaffer 1.6.20 .

Thanks

[John Haddon]

Hi Pablo,

Sounds like you're storing Pref as doubles? I suspect we just never added loading for that because we never use it - since none of the renderers we support can consume double data, there didn't seem much point. How do you use it once loaded? Is it converted to float for rendering? And how important is Alembic support for you in general? We're putting most of our focus on USD now, because that's what we use in production here...

Cheers...

John

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[Pablo Gimenez Pizarro]

Yes it is stored as doubles.
I'm not sure of the reason, talking with one o the guys here seems an old convention and our custom Alembic exporter does in that way.

My guess is that it is to keep it in sync with P that really needs to be in doubles for certain scales.
Houdini loads it as float64, not sure what Arnold does, I don't remember if it clamps it to float32, it has never been a problem on the render side to be honest, used in Arnold, Karma and Mantra.

[John Haddon]

Could you send us a small example `.abc` file containing PRef please? Then I can look at getting the SceneReader updated to load it...

Cheers...

John

[Pablo Gimenez Pizarro]

Thanks John.
Is there any procedure to send files for debugging/testing?

[John Haddon]

Sometimes folks just post them here, sometimes attach them to a GitHub issue, sometimes email direct, sometimes send us a download link. Whatever works best for you - I'm assuming you'll strip anything sensitive before sending...

Cheers...

John

[John Haddon]

Fixed the loading from Alembic here : https://github.com/ImageEngine/cortex/pull/1554.

Fixed the translation to Arnold here : https://github.com/GafferHQ/gaffer/pull/7121.

Cheers...

John

[Pablo Gimenez Pizarro]

Fantastic, thanks a lot for the quick fix.

I'm planning to update our gaffer version to the new 1.7 at some point next week.

To view this discussion visit https://groups.google.com/d/msgid/gaffer-dev/caa1d98a-68f4-4efb-b546-93b58a080eb8n%40googlegroups.com.

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Pablo Gimenez, Senior CG Technical Director

Important Looking Pirates - ILP

Email: pablo....@ilpvfx.com