Hi all,

hope this is the place to ask. I'm learning Houdini, and I'm sure I am just doing something wrong here.

I have a POPnet setup. Particles cached out, and I've adjusted the pscale and Cd. Nothing fancy with the setup.
The IPR render in Houdini looks fine, but rendering to disk (both locally and on the farm) only gives me “black” images. That is; the alpha information for the POPs are there, and if I crank the contrast and gain to the max in Nuke I can see the particles in my color pass as well, but of course very grainy and aliased. Nothing like the IPR render where the color pass looks fine.

My first reasoning was that the lights aren't included, but they're forced on the Mantra ROP. And all other objects/passes looks as expected. Not sure what I am missing here?

Any advice is greatly appreciated. I attached the same frame rendered by the IPR and the Mantra render

Could you share a ( simplified ) scene file with the problem?

Thanks! Actually, while creating a simplified scene for you it seems I stumbled across the source of the problem.
I have an alembic scene imported from 3dsMax, and using/rendering from a camera that's stored in the same Alembic file.

When recreating a new camera at the same position I noticed the render output was as expected. I compared the settings of the two cameras, without finding any differences. Still, need to use the animated camera from the Alembic file though. Is this a bug, or is there a known solution to it?

Ha! You just rubber duck debugged your problem

Sounds like the camera is scaled or is parented to something that has scaling.
Scaling cameras or lights can result in wrong lighting and shading.

I have not tried it yet, but there is a new feature in 16.5 that ignores camera scaling by default.

If you want to stay in 16.0 you can use a workaround:

- add a Fetch Object to /obj
- pick camera from inside alembic archive
- enable “Use parent transform”

- add a Blend Object and parent it to the Fetch
- disable SX SY SZ

- copy / paste the camera from the alembic and parent it to the Blend

Awesome, thanks!
That must be it! Thanks for the fetch explanation. I'm exporting a mantra job now, so I'll know how it goes in a while.