Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: ikercito on 2015-01-14, 15:27:21

Title: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-14, 15:27:21
Hi all,

I recently aquired a new machine to act as a render node to my main workstation. I've been since trying to get Distributed rendering to work, but something is not working.

My main computer has my whole 3D work drive networked, with all the files required available to my node. Node has DrServer and Backburner Server launched. Workstation has either DrServer, Backburner Server and Manager launched (i've tried different combinations everytime).

Before launching render I open Asset Tracking and either Resolve Paths to UNC location (which points the files to Z:\\workstation\...) or Retarget Common Root (to \\workstation\...) I've tried both, then I enable Distributed Render in Corona, Search LAN, and it correctly find the node (if DrServer is launched on workstation it finds it too, but i guess it is useless isn't it?). I launch the render....

It starts in both computers (can't really see whats on the node since it's minimized, but looks fine). In 60 seconds node syncs with workstation and this is what i get.... A black bar along the image everytime I do it.

Can anyone help me out please?
Title: Re: Need help setting up Distributed Rendering
Post by: lucamatto on 2015-01-14, 16:26:55
Hi, I have the same problem with some files...with others the image rendered with distribuited render  is more clear then the image rendered with only one PC (no matter wich PC is used).
Title: Re: Need help setting up Distributed Rendering
Post by: Lucutus on 2015-01-15, 08:05:41
On the first look i would guess your two machines have different gamma settings.

check input an output gmma settings on both machines.

greetz

Lucutus
Title: Re: Need help setting up Distributed Rendering
Post by: ikercito on 2015-01-15, 11:31:21
Thanks Lucutus for your tip, it looks like a very probable cause... But unfortunately gamma is set the same in both computers.

I've been trying a few things and still can't get it to work. I've made sure the paths are correct and reachable for both computers. Even checked DEBUG mode and looked at the temporary EXRs the node sends. They look very coarse and dark, is this supposed to be a normal thing?

What I've noticed is that the render starts fine on the workstation and once the node syncs, the black band kicks in, alternatively... first sync on the lower side of the image, second sync on top and so on... The original image progressively gets darker. That's why I'm guessing it is in fact a gamma issue, but as i said, gamma is set the same on both computers.

Could anyone give me a hint on what's happening?
Title: Re: Need help setting up Distributed Rendering
Post by: Lucutus on 2015-01-15, 13:20:48
have you tried to render the same image on every single machine seperatly and compared the result?

greetz

Lucutus
Title: Re: Need help setting up Distributed Rendering
Post by: ikercito on 2015-01-15, 14:04:26
I trying right that now Lucutus.

Launched the DR from workstation, stopped it, and now i'm rendering the scene locally on workstation, and the "received_scene.max" from DrServer/DrData on the node.

For now they look identical... we'll see after an hour. Will report back with the comparison results
Title: Re: Need help setting up Distributed Rendering
Post by: maru on 2015-01-15, 15:32:52
What 3ds max versions are you using (on both master and slaves)? Did you check gamma in 3ds max settings, in save image window, and in Corona settings?
Title: Re: Need help setting up Distributed Rendering
Post by: ikercito on 2015-01-15, 16:26:00
Hi guys,

This is the comparison from both renders. It's still quite raw and rough, didn't take time to set the lighting properly. I've checked with the eyedropper in different areas and both images are equal. Might be just a little difference of +/-1 every now and then, probably due to different noise patterns. But I think this leaves the "gamma drama" out of the question...

Now I'm completely lost on what the problem could be...

Maru: I'm using Max 2013 64-bit on both computers, both saved as EXR with gamma 1.0 and then converted to 16 bit in Photoshop. It's just the same if I save as jpeg with gamma 2,2. Can't find any gamma settings inside Corona though... (so I probably never touched them)

I'm currently rendering a Distributed render to compare with the previous separate renders. Starts to look much darker since the first couple of syncs.... :(
Title: Re: Need help setting up Distributed Rendering
Post by: lucamatto on 2015-01-15, 16:42:20
Hi, I'm using 3ds max 2014. The gamma settings are the same on both machines, if I render separatly on each computer the image is identical...but if I use distribuite rendering the image is incorrect...

Thank you.
Title: Re: Need help setting up Distributed Rendering
Post by: ikercito on 2015-01-15, 16:49:40
Hi Lucamatto, that's exactly what I'm trying to figure out.

This is a comparison of the Distributed Render against both the Workstation and Node renders separately.

Image from the DR is quite darker that the others, although doesn't seem to be a 1,0 to 2,2 gamma mismatch. Which leaves me quite stunned. I don't quite understand what's going on...

Notice the red arrow, it's showing one of the black bands that appear during the sync. Not very noticeable this time, but definitely totally incompatible with a production render...!
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: Lucutus on 2015-01-16, 09:54:46
@ikercito

Have you tried a scene without textures? Just to sort out the the texture import as origin of the error.

greetz Lucutus
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-16, 11:57:42
Hi guys,

Just like Lucutus said, I've tried a scene without textures in Distributed Render, and it came out OK!

Then... it should be something related to textures. But what? I tested a scene individually on both computers and they both matched. But if I launch it straight from DR the above thing happens. Is this some kind of bug?

I have no idea what's going on...
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: Lucutus on 2015-01-16, 13:36:52
in this case i guess it could be some issue relating the gamma input value for the textures.

Greetz Lucutus
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-16, 16:05:17
Hi, I guess you could be right. But, the input gamma should already be embedded on the file i'm sending to the node,... right? I mean... It works fine rendering on the node by itself. Or maybe you refer to the input of the file incoming from the node?

I've seen a few other posts about this same problem on the forum, but i think only one was resolved, and it didn't work for me. So it's not an isolated problem I guess.

Gosh... i suppose the developers are pretty busy preparing the launch of 1.0, but I'd be very grateful if they could shed some light in this :(
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: borisquezadaa on 2015-01-16, 17:21:06
Is it a possibility that the architecture of both workstation+render are different?. Meaning different processors (amd intel).
Cause there is some calculation involved  that adress specific instructions in CPU's that (Shooting in the dark here) maybe delivers sligthly different results between CPU architectures?.
I know for fact that irradiance for animation in vray MUST be calculed in one single pc cause of this issue. Maybe the hd/uhd cache is calculated in each pc just instead in one and are sligthly different.
For DR Corona calculates hd cache in each render node and then merges the results?... or just one pc calculates and then is distributed to render nodes?.
One way to discard this would be maybe using PT/PT?..

Other wild idea is that sometimes IES files doesnt appear on assets tracking. That could be a problem.


Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: lucamatto on 2015-01-16, 17:28:48
The problem appear in the moment when the slave machine start to render...I think that is not a texture gamma problem..the texture are in a network folder and the setting of 3ds max are the same... and if I render the image separatly with one of the two computer the image is perfect.
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-16, 18:37:03
borisquezadaa: That doesn't sound too impossible. Both processors are i7, but the sockets are different (2011 and 1150). Who knows... maybe that's the culprit? I haven't used IES for the examples, just HDRI, so that shouldn't be a problem.

I'm wild guessing here, but I suspect that it probably is something user related, something I didn't configure properly... Network? Permissions?

Don't know what, but it's driving me insane :(
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: maru on 2015-01-16, 19:22:19
Does it happen in other scenes? Can you prepare some new very simple scene and see if this effect is there?
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-16, 19:40:49
It happens in every scene I try. I've done a few different tests, different scenes, with and without textures etc... None worked.

The only correct image comes from rendering the scene individually on each machine, without DR.
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-20, 20:00:33
Hi again guys,

I still had no luck with DR. Should I report it as a bug?

Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-22, 18:21:45
Hi guys!

Problem solved! At least for now I seem to have found the solution to the problem. I was using an older version of the Multitexture plugin (it's been recently updated) and that was the cause. Seems like DR is finally working for me since I updated it. I hope it helps everyone else.
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: maru on 2015-01-22, 19:02:53
Congratulations on solving this. :) It may be very useful information. So on one pc there was a different version of plugin than on another pc?
Title: Re: Help setting up Distributed Rendering - Dark bands and incorrect colour in DR
Post by: ikercito on 2015-01-22, 23:40:02
Nope! It was the same version on both, but for some reason that version doesn't cope well with DR. Newest version seems to work fine. I launched a test render earlier today, and only the surface with multitexture rendered incorrectly. It's been the first time I could pinpoint the problem that easily. The thing is, this same problem (black bands and bad gamma) has been reported numerous times in the forum, but there's (I think) only one post with the correct solution (can't remember the poster). For some reason the solution didn't come out in the search results until I specifically searched for "multi texture".

BTW I recommend this plugin to everyone, i use it everyday, does a great job and it's free. :D