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Support => Terragen Support => Topic started by: StephB on December 09, 2018, 09:12:51 am

Title: Unsolvable Bucket artifacts?
Post by: StephB on December 09, 2018, 09:12:51 am
Hello,
I just registered here but I'm familiar with the forum and Terragen ;)

Nevertheless I'm struggling with artifacts in clouds despite all the tests I made and the tips I found on the forum.

The situation is this one : I have a scene with three cloud layers (one 2D cirrus, high level layer, one V3 medium layer and one V3 lower layer.
Rendering through a render farm, I now always encounter bucket artifacts with high res renders. Testing with 3000x1500 for instance. Artifacts are probably linked to GI in clouds, but I tested acceleration to none, GI file sent to the farm, higher "GI in cloud" setting, padding, etc.. to no avail.

At home, I never experienced that : all renders are ok, as far as they are done in one run. I experience inconsistent GI in clouds once when rendering a large image in several parts (cropping) but solved it with a pre-generated, huge GI file.
On render farm, I experienced that once and solved it with higher GI in cloud setting (very high) and probably acceleration to "none".

But now, I'm out of solution.
Any idea?

I read here that rendering a GI pass file at lower resolution (say 1500x1000) and use this file for farm-rendering at higher resolution (say 6000x4000) would work. Is that true? If so, it will be very helpfull as I can't imagine having to upload 2GB GI file for each render on the farm.... :/
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on December 09, 2018, 09:13:43 am
Attachment:
typical artifact in cloud (bucket size, square)
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on December 09, 2018, 09:15:18 am
Attachment:
banding artifact I found in a farm-rendered image when using a pre-generated GI pass file.
Title: Re: Unsolvable Bucket artifacts?
Post by: Matt on December 09, 2018, 02:16:35 pm
I think it's probably the Cloud GI Quality. You might need to set it even higher (e.g. Sequence x4, or higher).

I'm going to provide some way to store this data in GI cache files in future versions, but at the moment the only solution is to increase quality to reduce the per-frame/tile differences.
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on December 09, 2018, 04:32:54 pm
OK Matt, I'll give it a try. Thanks.
(I thought "sequence" settings was for animation, btw)
Title: Re: Unsolvable Bucket artifacts?
Post by: Matt on December 09, 2018, 06:04:43 pm
It is, mostly, but the sequence settings are really just higher levels of quality than the still image settings. I wanted to use the "still" vs. "sequence" naming to steer people towards using the lower settings for still images, otherwise too many people would use much higher settings than they need, resulting in unnecessarily slow render times.

Usually it's only in animations that you need the sequence levels, to prevent flickering frames. But tiled rendering has similar quality requirements to sequences because you notice differences between tiles that you wouldn't notice when rendering the image as a whole.
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on December 10, 2018, 05:00:27 pm
Unfortunately, increasing the GI cloud settings didn't help...  :'( :(

Tried Sequence x4, x8.
Title: Re: Unsolvable Bucket artifacts?
Post by: Matt on December 10, 2018, 05:04:43 pm
And you're also using a pregenerated GI cache file?

Can you send us a .TGD to support@planetside.co.uk? I'd like to figure out exactly what's causing this.
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on December 10, 2018, 05:06:10 pm
Can it be caused by the cloud settings themselves?

I noticed I checked the "accelerate empty space" box but tried also without and the problem's still here.
Title: Re: Unsolvable Bucket artifacts?
Post by: Matt on December 10, 2018, 05:12:26 pm
It appears to be in the atmosphere, but the light in the atmosphere is affected by other things. Usual culprits are:

1) Differences in GI in atmosphere. This should be solved by the using a GI cache file.

2) Shadows from another cloud layer:

a) The voxel buffer and/or 2D shadow map can change from one frame/tile to the next, but I've rarely seen such a big difference.

b) The most common cause of differences in shadows is the Acceleration Cache, so you should always set that to "None" on every cloud layer that could cast a shadow into the scene.
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on January 11, 2019, 03:38:01 pm
Hello,
concerning my rendering issue, I got no other option than generating the image in a single -long- run on my side. Got a quite nice render that I was able to use :)
But I'm a little bit concerned for future ideas... :-\

(http://stephanebeilliard.com/site/storage/cache/images/001/675/ConcordeRedux-019-SBeilliard-Web2018,xlarge.1545558112.jpg)
Title: Re: Unsolvable Bucket artifacts?
Post by: Oshyan on January 11, 2019, 05:11:11 pm
Are you able to share the TGD file privately with us? We can try to troubleshoot the issue further here. You should not have to do a single-thread render.

Beautiful end result though!

- Oshyan
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on January 12, 2019, 08:44:31 am
Oshyan, I actually already sent you the TGD file, following Matt's post. You did not receive it?
Title: Re: Unsolvable Bucket artifacts?
Post by: Matt on January 12, 2019, 12:06:36 pm
I received the file and have been working with it to try to understand the cause of the problem. So far I don't have a solution but I will keep on it.
Title: Re: Unsolvable Bucket artifacts?
Post by: Oshyan on January 12, 2019, 08:13:46 pm
Oh yes, that makes sense. Sorry, I thought it was a different file.

- Oshyan
Title: Re: Unsolvable Bucket artifacts?
Post by: StephB on January 20, 2019, 07:01:05 am
Thank you guys.
Title: Re: Unsolvable Bucket artifacts?
Post by: D.A. Bentley on February 26, 2019, 12:39:26 am
Quote from: Oshyan on January 11, 2019, 05:11:11 pm
Are you able to share the TGD file privately with us? We can try to troubleshoot the issue further here. You should not have to do a single-thread render.

Beautiful end result though!

- Oshyan


I don't think he meant he rendered the successful render on a single thread (one core/thread of a multi-core CPU).  It sounded like he rendered it just on his Home Computer rather than the Render Farm he was originally referring too.  I also had similar issues with render farm rendering of still frames and the fix was to just render on one computer.

-Derek