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LukeLetellier

Export Spline Groups in Alembic so they Import as Separate Objects

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Posted (edited)

Hello,

I have a large group of road splines (generated by the lovely OSM Importer), and I've separated them into primitive groups based on their function (highway, residential, etc).  I'd like to export all the road splines in a single alembic file (or another universal file format) in such a fashion that when it is re-imported (in my case, into C4D) the different splines are separated into separate Alembic spline objects. 

Currently, they import as a single object (even when I try importing them back into Houdini). I've also tried exporting them as point groups, but still they come back merged as a single object.

Since there's thousands of splines as part of the OSM file, I can't simply split them up in C4D post-import & manage them that way.

The only way for sure I know now is to export each spline group as a separate Alembic file (10-12 files total), and bring them into my scene one at a time - but I'd much rather have just one file. 

Demo file for testing: hSpline_Export.hiplc

Demo Scene Node graph pre-export:

Y23SRYD.png

Demo Scene Nodes once they are reimported as Alembic:

jAMEhCp.png

kjv0fKD.png

D0n0rMh.png

 

Any thoughts?

Thanks!

Luke

Edited by LukeLetellier

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Posted (edited)

On your Alembic ROP, enable Use SOP Path and Build Hierarchy From Attribute. You can make a primitive string attribute called whatever you want (let's say "abcPath" for this example) on your curves, and give each object you want separated a unique path attribute ("/geo/highway/curve1" or whatever). This string attribute will then determine the hierarchy of your exported objects; just set the "Path Attribute" on your ROP to be "abcPath" to match and you're good to go.

Edited by toadstorm
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How does one enable "Use SOP Path"? Its grayed out on my end. I've tried enabling the other options, thinking that one of them would do the trick, but I can't find the magic button.

EqgIWfM.png

 

Thanks!

Luke

 

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I think that option is implied when you're using a ROP Alembic Output SOP... you'd only need to explicitly check it if you were using an actual Alembic ROP in the /out/ context.

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Yup, you're right. Everything works as you mentioned! I don't even need to split them apart manually at all, as the OSM importer already generated an attribute called "highway" that I can use. 

Thank you Henry!

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