packed alembics rendering slow

[ronald_a]

Hey,

we have noticed, that rendering packed alembics with displacement takes a lot longer (about twice as long in our case) than having unpacked geo. I have a packed up example I can send.

[ronald_a]

Hi, did somebody have a chance to look into this?

[bdancer]

> I have a packed up example I can send.

Sure, will be interesting to look into it.

[ronald_a]

bdancer Great, I will send you the file via mail. I want to add, that using cached normals makes the alembic render at normal speed. with my specific asset, the look is just not the same (I tried to increase the max subdiv massively, but that would lead to it not rendering at some point).

[david.anastacio]

Hey ronald_a,

How bad is it for you? Alembics being slower than "live" geo is normal, one is already in your memory the other needs to be read from an exterior file and if that file is in a network location even slower it will be, and if you are in a windows machine that has no caching that file needs to get loaded every time you hit the render button.
We saw some real render time differences just from having an alembic local on the workstation vs on the network.

Best,
David.

[ronald_a]

Hey david.anastacio , it's actually the renderspeed that makes a vast difference. In this particular case it takes about double the time to render. The asset itself is actually pretty light, so loadtimes are not relevant. and again, If I render with cached normals it is actually as fast as the unpacked thing. But I don't think it's an option because it looks different and we had other issues with that.

[david.anastacio]

Hey david.anastacio , it's actually the renderspeed that makes a vast difference. In this particular case it takes about double the time to render. The asset itself is actually pretty light, so loadtimes are not relevant. and again, If I render with cached normals it is actually as fast as the unpacked thing. But I don't think it's an option because it looks different and we had other issues with that.

This a different thing then, curious on what it might be then.

[Ambrozie]

I have a somewhat similar issue. Packed volumes seem to render much much slower. If I manually copy a few volumes they render in a time "t", if I use copy to points (a few points to keep comparison fair) or instance the render time is "t * 5". Also, overlapping volumes look weird.

[ronald_a]

bdancer, did you have any chance to look into this yet? We are having more render slowdowns on another project which seem to be related to alembics (but without displacement). I need to dig a bit deeper and can send another simplified file to take a look at.

[bdancer]

Well, I haven't got any scenes so I haven't looked into this sorry...

[ronald_a]

bdancer seems the mail didn't get through to you (maybe spam filter). I just sent the mail again so you should have something to look at (this is about the displacement/Alembic slowdown for now).

[ronald_a]

Hi bdancer, did you have any findings with this issue?

[bdancer]

On my machine results are:
unpack: 0h 2m 29.9s
packed: 0h 2m 55.8s
On average looks the same as here...
Anything specific about your machine? many cores? numa?