[feedback] Corona VFB switches to black

[CASA_MT]

Hi @ all,

I have encountered a strange behaviour in Corona 1.5 (1.5.1 and 1.5.2) with 3ds max 2017 SP 2.
I rendered a Hi-res image (4900 x 3500 px) and when starting the render process everything is fine. After 30 passes or so, some of the render elements (including beauty, lightmix and reflect/refract) turn black. When scrolling through the elements, they will be visible again, but will disappear after a second or so. When I try to save the .exr files, they will turn out completely black. I hoped that it would be just a display issue, but the image itself does not contain any information except black.

I already made a completely new file, tried it only locally, with DR and via backburner, it is always the same. There are only Corona-compatible cameras and materials inside the scene and the camera is not occluded by any other geometry.

Any ideas how to fix this? I did not encounter anything similar so far

[CASA_MT]

Ok, seems like no one ran into this before.
Just if anybody experiences this problem:
So far the only way to at least get the files out of the framebuffer is to keep an eye on the FB and save the VFB every ~ 10 passes or so. When the VFB turns black again, close the file, restart MAX and resume the renderjob from file.
It is not very fun to do this, but at least it works.
I am still interested if there is anything to prevent this, we do not have this issue with any other file.

[maru]

Sorry for the delay!
What file format are you using to save the render elements?
How is your RAM? Are you sure you are not running out of it?
Other than that, any Corona error messages visible?

[CASA_MT]

Hi,

I wanted to save them as .exr but also tested .tiffs, does not make a difference.
I have 48 GB of RAM and the scene is relatively simple, It took around 7 GB of RAM.
As I said, I already tried it via backburner or DR, picture still turns black.
There are no Corona-errors whatsoever which is the strangest thing.
As I had to try several things, I noticed that Corona will not render more than a certain amount of passes (e.g. 27) within one session before the VFB turns black. This is why I had to restart MAX and give it another try. In a new MAX-instance it will render past the level of passes which caused the black VFB.
Veeeery strange.

[sevecek]

Are you using Bloom & Glare? If so, could you please check if the problem appears also with B&G turned off?

[CASA_MT]

I was using a lot the VFB-features.
I will try turning off all of them and see what happens. I will post an update as soon as I see anything strange.

[Ondra]

I would be interested in the scene and also info about what coroan version are you using

[CASA_MT]

hi,

I rendered the frame over night without the VFB Post-FX and it managed to get to nearly 200 passes without a black VFB.
I stopped it and could save the image. As soon as I turned on Bloom and Glare the VFB became black again, all other FX seem to work fine.
At least you gave me the right direction if this occurs again, thanks a lot.
I still find it strange and of course we want to use Bloom and Glare from time to time.

Is there any advice how to avoid this behavior? I just want to make sure that we can use VFB FX without being worried that the picture will turn into black.

@ Ondra: Corona is 1.5.2 (but it also happens in 1.5.1). The scene is around 200 Mb large, no scattering, no proxies or any other fancy stuff.

[Ondra]

Can you upload the scene (see my sig)? Or wait for next daily build (hopefully today) - there is another NAN fix in it

[råformat]

Hi
I have exact the same problem as CASA_MT. I have try to render big and small, with or without sun/hdri. My RAM is 64GB on one computer and128GB on another and they never peak.
I´m using Max2017 with Corona 1.5 hotfix 1
Tried to save as jpeg or tiff. Printscreen does work though... Lucky to have a 30" screen, so I can give something to my customer... ;)

Any soulution?

all the best/Ola

[råformat]

Hello again
Tried to render without bloom&glare - works perfect!
Strange is that I have another camera in the same scene that render and save with bloom&Glare...

But it would be great if there was any solution to this problem.


regards
Ola

[Ondra]

I am still waiting for a scene that produces black pixels so I can fix the problem ;)

[Ondra]

no info, presumed fixed in 1.6

[Michał Morzy]

Hi guys,

I know that this topic is quite old but I seems like it hasn't been fixed in Cr1.6. It occurred for the first time in one of our scenes. Exactly the same problem. After few passes the VFB turns black. Anyone has any more recent solutions?

Cheers,
Michal

[maru]

I experienced exactly the same thing once, and I have it reproducible in a scene. It is already reported in our internal tracker, along with a link to this forum thread. Any updates will be shared here as well.