Vray bad lighting in some render buckets

#1

Hey all I am hoping someone could help solve a problem we have been having with Vray distributed rendering for quite some time.

We have a handful of render farm computers and when we use them to render our vray scene out over the network, some render buckets are returning with either a brighter block or a darker block.

I want to make sure everyone knows that these ARE NOT missing textures. Its more like the gamma is different. Why would some of these network rendered block be returning different lighting?

I’ve attached a picture. Thanks for the help!

#2

Are you using Light Cache as a GI by chance ?

If so you have render the light cache file out on one machine and load it at render time for all the other computers.

#3

That is precisely what I am doing. Light Cache is my secondary bounce. I will try loading the saved file.
I assume I have to render it locally first, save then do distributed rendering?

I also tried doing Brute force as my secondary but ran into the same problem at times. Maybe I need to save the primary irradiance as well.

#4

Yes, set one machine to render the whole sequence GI only and cache out the light cache then set to load at render time.
Might be the way to go and cache out the primary bounce as well then distribute the final render.

I’ve only ever needed to render out short frame ranges though so I can’t say how it will impact on a longer run.

#5

OP did this work for you?

#6

Unfortunately not. There are a couple reasons why it doesn’t. The light cache file makes the distributed render machines hang and only my local computer is doing the work.

Workflow wise: When I add new lights to the scene, that light cache file I previously saved is out of the window and I would need to re-render the light cache pass locally all over again.

I even tried doing Brute Force Primary/Brute Force secondary and it still happens.

The funny thing is that sometimes, the distributed render nodes all work out fine with the correct gamma. So I can’t quite figure this one out still. I find that restarting Maya and then using distributed rendering works.

:shrug:

#7

I had this issue a few months ago and never got to the bottom of it either, though my suspicion was that it was related to 3D textures in my scene and/or alembic files. However, mine wasn’t a distributed render it was an animation rendered on a farm of 8 or so computers.

I ended up starting the shot again without any 3D textures and it seemed to work. :shrug: