Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: adamadam on 2016-11-02, 12:19:28

Title: Black squares on frame buffer and saved image
Post by: adamadam on 2016-11-02, 12:19:28
We've had the odd black square appear on some frames (only 3 of 250) of an animation. It's only in the beauty pass in the frame buffer, but it saves out with the square embedded. The square moves around but is the same size in all of the frames where it occurs.

The square has appeared when rendered on our render nodes (which are running 1.5 hotfix) and on the workstation (running 1.5)

I did a search and couldn't find anything else like this. Anything we are doing wrong? (We'll be updating the workstation to the hotfix as soon as this animation is finished - wanted to match the existing colours.)

Thanks,
Adam
Title: Re: Black squares on frame buffer and saved image
Post by: pokoy on 2016-11-02, 12:49:01
I had exactly the same problem once, it was caused by an NaN pipxel and only if denoiser was used. The square should disappear if you disable denoising.
I hoped to be able to reproduce this back then but couldn't so it wasn't fixed.
Title: Re: Black squares on frame buffer and saved image
Post by: adamadam on 2016-11-02, 12:52:28
Thanks Pokoy. Yes, it was denoised.

If I can get it reproduce, I'll post the scene, but those frames have re-rendered without a problem.
Title: Re: Black squares on frame buffer and saved image
Post by: FrostKiwi on 2016-11-02, 12:57:02
Thanks Pokoy. Yes, it was denoised.

If I can get it reproduce, I'll post the scene, but those frames have re-rendered without a problem.
Could you reproduce the error and check, whether the right click pixel inspector reports a NaN? If yes, this is a major issue and has to be found and bug fixed. So many algorithms after rendering depend on the pixels having a real float value. If it becomes suddenly not a number many problems arise.

Could you render the same error and upload a corona .exr dump of it? Stuff like this has fixing priority.
Disabling denoise is not the solution, as denoise works fine and it just fails at not expecting a NaN as input.
Title: Re: Black squares on frame buffer and saved image
Post by: maru on 2016-11-02, 13:20:15
I don't think this has anything to do with the original problem, but it's not a good idea to use DR with two different versions of Corona (1.5 vs 1.5.1).
Title: Re: Black squares on frame buffer and saved image
Post by: Fluss on 2016-11-02, 13:50:55
NANs are so bad... I always encounter problems when i comp V-ray rendered animations in nuke... Could be cool to detect those NANs pixels and replace them with a float value (something like average color value of the surrounding pixels), in all passes of course.
Title: Re: Black squares on frame buffer and saved image
Post by: pokoy on 2016-11-02, 13:52:45
Yes, either that or add a method to denoiser that would help to handle NaNs that way.

Do you have a global volume material applied by chance? In my case it was an interior render and I've used a global volume material. For some reason I couldn't reproduce it after I submitted a bug report, but it happened almost every time before that. Strange stuff.
Title: Re: Black squares on frame buffer and saved image
Post by: Ondra on 2016-11-02, 14:24:23
as always, I would be very interested in any scene that produces NaNs, and I can fix any such bug swiftly!
Title: Re: Black squares on frame buffer and saved image
Post by: adamadam on 2016-11-02, 15:10:25
Maru,

Not DR, just separate frames on Backburner. So no mixing :)

And yes, I know it should be upgraded (just keeping it like this for this project to match existing output).
Title: Re: Black squares on frame buffer and saved image
Post by: adamadam on 2016-11-02, 15:15:21
No global volume material in this scene Pokoy.

Will try and see if the error can be replicated, but it has been rendered again without the square (nothing in the scene or any settings were changed between renders) and only three of the frames (out of 250) had this problem.

If I have time, I will try and reproduce and send scene if I can.
Title: Re: Black squares on frame buffer and saved image
Post by: adamadam on 2016-11-02, 17:08:59
It happened again so have uploaded EXR dump as suggested to Mantis. I can send scene if you need it.
Title: Re: Black squares on frame buffer and saved image
Post by: Ondra on 2017-03-21, 15:35:23
can we get a scene where it happens so we can fix it?
Title: Re: Black squares on frame buffer and saved image
Post by: adamadam on 2017-03-22, 12:41:26
Sorry, I can't remember what file was causing that (quite a few jobs ago).

We're all upgraded to latest hotfix now and we haven't had a problem with this recently. I will upload if I get a re-occurrence.