[flower]

Hope someone has come across this and knows the answer.

Rendering on single machine works fine.

Rendering using cooperative mode on a renderfarm has produced the following vertical grain all over the image. This is SL 20!




This is not maxwell noise. It has been suggested that a material is at fault.


I have 2 materails, with ior file. Essentially same material with different settings.

Other possiblities:
ISO is set at 1600 as this is a very low light image.

Some textures are maybe up to 2k pixels high or wide. Nothing unusal.

Got some emitters various intensities.

Any ideas anyone?

Thanks in advance.
Bim

[Bubbaloo]

I can take a guess that you have lights in the scene that are not quads or tris. N-gon emitters will cause this.

[flower]

Hi Brian,

Thats useful to know. Thanks for your quick reply.

I have made all emitters quads or triangles. But I have grouped them the create a single piece of geometry so that one multilight slider affects several 'lights'.

I've done this before and not had problems, but maybe I have done it differently this time. Will check.

Regards,
Bim

[flower]

Brian,

Further to what you say about n-gon emitters causing this.

To your knowledge does this happen only on Co-op renders but is ok on single machine renders? Because thats what's happening here.

regards,
Bim

[Bubbaloo]

No, I don't think so. I think it will happen on any render.

I have also seen this noise effect when using a renderfarm service (not mentioning the name). But I've never had it happen on my small render farm.

Does it always happen or just this scene?

[flower]

Just this scene, and only at the farm.

Does not happen on my machine at home. I've not had this happen before, either at home or at the farm.

I tried this scene on another render farm and the same thing happened, so I'm thinking its more to do with the co-op process. Weird.

I have another view I need to do of that model but I'm not sending more to the farm until I know that this is sorted. What a pain, deadline is tomorrow pm.

My machine is Mac Octo 2.8. Scene is only 40Mb, so not that big.

Cheers,
Bim
panicking...

[Bubbaloo]

Are you using a commercial render farm or a farm at your work?
If you have access to the individual mxi's, you can try merging them manually.

[flower]

I'm using a commercial renderfarm.

Used them a lot before, never had a problem, and they are being very very helpful. Cant fault their customer support.

They have seen this once before and believe it to be one of the materials, causing the problem. They are trying hard to find the cause, but some client is hogging the farm and they cant get access to it test my scene.

[Bubbaloo]

The time I had that problem was in a scene with a bunch of glass. Maybe that will help you narrow it down. I have even had some odd effects with instanced glass, so look out for that too. I am just trying to think of anything that could be happening.

[flower]

Thanks Brian, your help is appreciated.

I've remodelled my lights, waiting for a slot to come free shortly on the remderfarm to see if that has helped.

No glass in this scene, so that cuts that one out.

Cheers,
Bim

[Bubbaloo]

Also, make sure your emitter planes are not intersecting any other geometry.

[flower]

ahh that might be, currently redoing my emitter geometry again so that it dont intersect nuffin.

See how we go. Will post results.

Cheers.

[flower]

Okay still at square one. NEXT LIMIT... HELP PLEASE.

I remodelled all my emitter planes and made sure they were not touching or intersecting any geometry or each other.

I remodelled some dodgy looking geometry.

Still got the same problem.

Some tests I did.

1. removed all texture from the file by making everything 218white,and only lit by emitters. No change, still got the grain. Deduction - its not a material or texture problem.

2. removed all the emitters and took the roof off and used sunlight. No grain. Deduction - it must be something to do with the emitters (or the roof material/geometry - unlikely)

So its something to do with the emitters.

The scene is an enclosed space, a cabin on a large yacht. Two small portholes either side. I have some big emitter planes outside simulating daylight. Environment setting type to NONE. Inside I have a series of ceiling lights, planes pointing down, all joined to act as one emitter. There are a couple of other emitters giving some little highlights. And a series of planes behind a pelmet giving a glow on the interior of the hull side. So 6 Multilight sliders.

As its quite dark, ISO set at 1600, Shutter varies between 5 and 10, F-stop is 2.8. I have to turn up the ceiling lights quite a lot to get good illumination.

Does high ISO add in grain like a bad digital camera?

I've tried lowering the ISO to 400 and lowering the shutter to 1- 4, but I have to increase the emitters to get any decent light.

Scene scale is correct.

I'm stumped.

Any Next Limit guys have an idea what is going on?

This is serious. I tried on two different renderfarms, both gave the same result. Both renderfarms use a different merging technique, so something is going wrong somewhere with the coop. As I said works fine on a single machine.

This is a major client and my deadline is tomorrow pm. I need this to work on a renderfarm to have a chance of meeting my deadline.

Look forward to some insights.

Regards,
Bim Daser

www.fluid-future.com

[Mihai]

ISO/SS won't matter for noise levels. You could try merging all the emitters, although I can't guarantee that will get rid of this strange pattern. Take note of each emitter strength when the lighting is as you want it, then multiply the emitter materials strength with that value. So if the emitter slider was say 457, multiply the emitter strength by 4.57x. Either the lumens or the wattage, depending on what units you use in the emitters.

If you can please send me this scene for debugging. It will remain confidential.

[flower]

Hi Mihai,

Thanks for your quick reply, and your offer to look at the file. How and where can I send the file, it is 32Mb?

Regards,
Bim Daser