Instance shapes scaling randomly per frame

[pixeldrone]

Hello, I have a scene that has many instance geo on particles. I am attempting to render this on my render farm. when I send the vrscene creation to the farm and then the vray standalone render job I get a render that glitches on every frame with the geo scaling up and down per frame, as if pscale were randomized on every frame. However when I export the vrscene from my local workstation and send that to the renderfarm I get a stable render where there are no glitches. I have been looking into basic config stuff on my farm versus my workstation but I haven't been able to see any differences. I am using Houdini 18.5.351 with vray 50050 on windows 10. I am using Deadline as my farm manager.

If anyone has any ideas on what this is, I would love to know. thanks

Best, Christian

[glacierise]

That's something that could happen when V-Ray versions for the standalone and the local VFH mismatch - usually we assign the VFH version as a standalone, to make sure they match.

[pixeldrone]

That was a great idea, I was running standalone instead of standalone from vfh. So I corrected that and ran another test render. Unfortunately, I got the same result. Another idea I had was to produce a vrscene file of the same frame locally and then from the render farm and run a diff on them. I ran the diff and there are differences between the two, specifically it seems with assigning meshes to the instances. I would love for someone at support to look at these files but they are too big to upload here.

Thanks.

[glacierise]

What if you replace the alembics with boxes, will get small but the pscale would still be in effect.

[pixeldrone]

ok, the boxes worked fine, no glitches. The difference is that I am not using packed alembics. I am using internal referencing with the op: syntax. In my point wrangle I changed this snippet:

int inst = int(rint(fit01(rand(@id), chi('Min"), chi("Max"))));
"s@instancepath = sprintf("op:/obj/Dirt_Geo/OUT_DIRT%s", inst);"

to this:
"s@instancepath = sprintf("op:/obj/Dirt_Geo/OUT_BOX");

Does this mean I should use packed alembics of my geo instead? I am trying to feed four or so variations of the geo on my particles.

Thanks.

best, Christian

[glacierise]

Yes packed alembics work great for standalone rendering

[pixeldrone]

I tried this with packed alembics and I got the same result.
so I had an idea to see if the geo was scaling or swapping on every frame.
I assigned different colors to each and did a test render and found that
the geo was swapping and not actually scaling. I am deleting the particles after
they reach a certain height so I know the particle numbers are changing, which is why
I made sure to use the @id for the random assignment as this should not change after
particles are reaped (or that is my understanding). So, as a workaround I scaled the particles
down to 0 instead of deleting them so that I could retain particle numbers. I did a test render with
this and the render came out fine, no glitches.

The box example worked because I was not assigning different types of geo to the particles.

So, having said all that, I am not totally sure why @id works when I do a local scene export and why
it does not work when I send the exporting to my renderfarm. Could this be a bug? I double checked to make sure that
@id was not changing and did animation previews before sending and everything looked good. I also noticed that vrscene files
make note whether or not the scene is being exported interactive or not, so maybe that's a factor too, I am not sure.

I am using an instance SOP with a point wrangle to assign geo to the particles.

I know you are pretty experienced with this workflow so I am hoping with this new information you might have some idea
of what's going on here.

Thanks.

Best, Christian

[glacierise]

You can mimic the different shapes by having a box and a sphere, and see how it works. If you post a scene or a screenshot at least it would tell the story better - not sure how exactly you're doing it, and there's so many options