[Sidefx-houdini-list] Transform Alembic /obj level geometry

Matt Ebb matt at mke3.net
Mon Dec 23 17:30:34 EST 2013


You should be able to access internal transforms inside the alembic file in
H13 if you use the new packed primitives.

I have to say though, they really haven't made it that convenient to access
and manipulate this data - you have to modify the P of each primitive's
associated point, and a primitive 'intrinsic' 3x3 matrix attribute called
"transform". There are very few tools that can easily work with those
intrinsics and they're very clunky - most of it seems to come down to a
couple of VEX commands.

Having it split across both point and primitive attributes also means that
often you can't just use the one tool (like a VOPSOP) to manipulate them.
You have to have something like a VOPSOP for the position followed by a
primitive Attribute Wrangler or something. This also means if you're
generating these transforms based on other data calculated in that (eg)
VOPSOP you have to save temporary attributes for the next node to pick up,
and then delete those attributes afterwards. Not the kind of elegance that
I expect from Houdini :(

Would be a lot more convenient if it just used some standard point
attributes like P/orient/scale!

cheers

Matt





On 23 December 2013 23:56, Nick Nimble <nick at nicknimble.com> wrote:

> Hi!
>
> I'm trying the Alembic exchange workflow in Houdini and so far I love it.
> Nevertheless I'm wondering if I'm the only one who is missing transform
> parameters when importing archives at object level that contains a object
> hierarchy.
>
> I completely understand the lack transform parameters when, in larger in a
> studio environment, you use Alembic to import def animated geometry. How
> ever, what is the approach when you get some model out of Maya through
> Alembic that needs to be repositioned and/or animated? During the modeling
> process most pivot points and orientations of groups have been set, but
> currently it seems to me that all this is lost during the Alembic exchange.
>
> Looking forwards to your thoughts and hopefully a workaround.
>
> --
> Cheers,
> Nick, be Nimble
> +31 622 4243 94 | www.nicknimble.com | www.facebook.com/nicknimble
>
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