Points workflow for instancing.

[david.anastacio]

Hi,

When dealing with alembic files that are used to drive instances nodes or copy to points SOP nodes this alembic files need to get unpacked so each individual point is read, this unfortunately leads as always, that unpacked data is going to be written into your vrayscene files. My question then is, is there any way to avoid this? This can lead to some really huge files when dealing with animated points.

Is there an alternative way to do this that doesn't involve caching the instances out to a new alembic file? Any suggestion is appreciated.

Best,
david.

[Dubbie99]

Subscribing to this thread also.
I have been also trying to figure out a solution for this.

[glacierise]

No way to keep the points in the alembic so far from what I know, unfortunately.

[david.anastacio]

No way to keep the points in the alembic so far from what I know, unfortunately.

That's been my conclusion too, was just trying to fish for any ideas or any hidden an convoluted way to do it.

Gosho.Genchev, is there anything you guys could do from your side to address this? I don't mind not seeing the instances working on the viewport (we can always use the current method to check if the setup is ok), something that would just work for the farm properly would do it.

Best,
David.

[glacierise]

From talking to Andrei last time we discussed it, my impression is that it's not a part of the current implementation, so you can't do it. Reworking this so the points stay in the alembic would decrease time/size of large instancing scenes and save a lot of time.

Thanks

[Gosho.Genchev]

Hey david.anastacio , Dubbie99 , glacierise ,

I honestly can not say much at the moment.

Assuming it would be possible to feed the V-Ray Instancer (I'm talking about the internal plugin) with an alembic file instead of collecting all the points from the scene, a couple of things pop to mind:
1. How do we know what geometry to place on the template point ?
2. How do we know what materials to assign to the geometry on that template point ?

When the Alembic file is unpacked, Houdini adds all that information for us to read. With a Delayed Load alembic, there's only a single point per packed primitive. Should we leave it up to you to add string attributes to the points in the alembic file ? If we do that, you will also have to Force export the instanced geometry, similar to how support for "shop_materialpath" with Delayed Load alembics works at the moment ?

Best regards!

[david.anastacio]

Hi, thanks for the feedback Gosho.Genchev

The points you raise are very good, and this definitely has no easy answer.
Letting use the delayed load primitives mode and then read from inside the alembic file the "shop_materialpath" and "instance" string attributes would be one approach.

Workflow:
alembic > unpack >set instances > set materials + cache points

Cache this to a new alembic file in the end and use that as packed disk primitives. The amount of data is still the same to be stored, but this can be done once vs every time a render is done.
This is far from the most elegant solution, the current one is actually the most elegant as users don't have additional steps, the data just gets dumped to the vrscene files and always works (the vrscenes do get huge sometimes).

Best,
David.

[glacierise]

Talked about this in a recent call with Gosho.Genchev - we'll try a workaround that saves the instances to a vrscene, and then reads this one and embeds in the rest of the geometry. I'll test that.

[Dubbie99]

That sounds like a good solution Hristo.

[glacierise]

Yes we just need to figure out overriding the shader for it