Local buckets rendering differently...

[evanerichards]

So we just upgraded to the latest nightly build so that we can use it with Maya 2013.
When I render though, strange things are happening. The render looks like this:


Certain buckets are rendering darker than the others.

So I rendered out a Distributed Rendering bucket pass.


So it appears that the only ones rendering dark, are rendering on my local machine. I cannot figure this out.
This shouldn't be happening. There is only one light source in the scene (an HDR). So, if the local machine wasn't finding that it should just render black but I don't know what would cause it to just render darker.

Any ideas?

Thanks in advance!

[yolov]

HI evanerichards,

Does the same thing happen when you're not rendering in DR (just one machine)? Are you using a texture on the objects where the wrong buckets are and is it possible they are somehow missing? The local machine rendered other buckets, from what I can see on your images but only seems to be incorrect on two places of the scene. Would it be possible to give us the scene so we can try and figure out what the problem is?

Best regards,
yolov

[evanerichards]

Well there are no mapped textures. Only procedural textures. So there shouldn't be a problem with some computers not loading textures. The only textures you could see in the render I posted would be the texture coming from the HDRI.

The same thing does NOT happen when I just render locally, but when I render locally the entire render looks to be about 1 stop darker than the buckets that would render on the farm.

Do you have an email yolov where I can send the scene? It is just a little too big to be posted here I think.

Thanks!

[yolov]

You can email it to me at alexander.yolov@chaosgroup.com. There may be some limit to the size of what can be emailed and if so, you can upload it somewhere (like dropbox) and send me a download link.

Best regards,
yolov

[evanerichards]

So just as a test, I made a brand new scene. I created a rectangle for a ground plane. I made a cube on it. And created a dome light and a vray physical camera. I applied vray materials to both pieces of geometry and made the ground plane reflective. The ground plane is rendering differently on my local computer than all the distributed rendering buckets. I tried it on another computer hooked up to our farm. Same deal.

This leads me to believe it isn't anything with my scene (as it did the same thing with a brand new simple scene created from scratch).

[yolov]

Ok, I've got the scene. I'll look into it and write back to you as soon as we have some useful info.

Best regards,
yolov

[Morbid Angel]

looks to me like a gamma issue on the dr machine.

[evanerichards]

@ Morbid Angel - Ok. So, two questions about that.

1. Why would the gamma be different? If the DR machines are pulling the render settings from my local computer shouldn't the renders be the same?
2. Why would the gamma settings affect the glossy/reflective areas but not materials with no reflections?

We've done some more tests. This issue is happening on any computer running maya 2013 and vray 2.25.01 but isn't happening when we run maya 2012 and vray 2.20.01
So it seems like it is a nightly build of vray 2.25.01 problem.

[yolov]

Hello again,

The problem is the irradiance calculation phase in DR, this is a known issue that was relatively recently discovered. The thing about it is that it doesn't occur on every scene and is a bit unpredictable, but we're hoping to fix it as soon as possible. There is a workaround until we manage to solve the problem: you can either render without DR, or if you're using a recent nightly build (i.e. from the last week or so) you can uncheck the "Use local machine" in the DR settings (this way the discrepancies in the irradiance map should be avoided). Another solution is to use Brute Force instead of the Irradiance map for example.

Hope this helps! We will write back to you as soon as we fix this.

Best regards,
yolov

[evanerichards]

@yolov - Well that's kind of disappointing. Rendering without DR isn't really an option for us since our scenes are taking so long to render. Guess we'll have to download the latest nightly build and then install it on all the CPUs on our farm.
Also, it seems predictable in the scenes I tested. All I had to do was create a reflective material and do a distributed render and it has done it every time so far.

As far as using Brute Force instead of Irradiance map...you must be talking about GI? Because in this particular scene I'm not using GI. So I guess that isn't a solution either.

[yolov]

That's kind of odd, because we have never been able to reproduce this with no GI. Can you copy the log from the maya output window when V-Ray is loaded. For example:

[2012/Oct/17|18:07:54] V-Ray: V-Ray for Maya version 2.10.01, revision 18370 from Jan 5 2012, 17:23:49
[2012/Oct/17|18:07:54] V-Ray: V-Ray core version is 2.00.01

Best regards,
yolov

[evanerichards]

[2012/Oct/17|12:35:17] V-Ray: V-Ray for Maya version 2.25.01, revision 22441 from Oct 17 2012, 02:03:57
[2012/Oct/17|12:35:17] V-Ray: V-Ray core version is 2.00.02

[yolov]

Is this the build you have used when you got the unwanted result? If not - can you confirm that this one doesn't work for you as well?
I was unable to reproduce this with 22441 and with older builds. You are however using some textures in your scene (which I've have replaced with other for some of the tests).
Side note: such problems can occur when different versios of V-Ray are used on the client and slave machines; somtimes it happens if the decimal symbol on the client machine is set to "." and the network one is set to "," in the regional settings (windows os).

Can you verify that those two possibilites are not causing the issue?

Best regards,
yolov

P.S. either way - 22441 has the "use local machine" which you can uncheck to exclude it from the rendering process.

[evanerichards]

Sorry. I updated my vray on the farm and on my local computer just before I posted the numbers there. I am still getting the same problem however.
The version I was using before was 22278 (2.25.01) that also had the problem.

I don't believe it is a texture problem as I can reproduce the problem with a brand new scene with a single object and a single glossy texture.

Like you said, it does solve the problem to turn off rendering on the local computer, but it would be nice to figure this out.
I'll look into different settings being on the DR machines.

Thanks

[yolov]

We'll keep looking into it, I also doubt there is a problem with the textures. It's just that your scene renders fine on our end without GI, and with GI there's the IrrMap issue. I look forward to your system settings check.

Best regards,
yolov