Output Black randomly with Lens Effects - VRay 3.10.03

[Morne]

Hi all

I have an animation with lens effects enabled from the VFB (not from Max Environment and Effects)

Randomly every 8 to maybe 10 frames, the output saved will just be black, from only certain elements.

I'm splitting the elements and basically all elements are fine except for RGBColor, Bloom and Glare. The last 2 obviously created on the fly.
Also, I'm saving out the entire frame buffer from max, that one is also just black.

All other channels and corresponging frames are fine. When the random blackness occur, is only on save. When I sit and watch the frames, it renders fine, but then when lens effect get applied at the end of the render, then that's when the random weirdness happen.

For example with a 200 frame animation, about 15 to 20 of the frames will be black (although the elements are fine)

Hope this make sense.

I also have hair and fur in the scene with dynamics enabled and in mr prim mode. My VRayCam has MoBlur enabled.

Thoughts?

[Morne]

I'm convinced its the lens effects. Had 3 frames in a row now going "black/blank" at the end of render

Although right at the end it also says something about hair/fur / which is strange because in mr prim mode the hair renders during the render, and not afterwards like in the old days with buffer mode

So not sure now which one is causing issues

[Zdravko.Keremidchiev]

Actually we had a similar issue with another client, where he gets a black beauty pass with a specific settings (Lens effect option enabled). Can you reproduce the issue if you decrease the resolution or the AA sampling?
It will be best if you could send us an example scene so we could have a look and investigate further.
Also please let us know the exact V-Ray version that you are using and provide some steps to reproduce the issue.
Moreover, please mention this thread in the e-mail.

[Morne]

I had AA on 2/100 and got the issue every single time on a specific frame I was testing.
When I dropped the AA to 1/4, the issue went away and everything was fine (except obviously I didn't have a clean render)

Doing some more tests. I might send a scene through a bit later...

[Morne]

on 2/50 its black again

[Morne]

2/32 black

[Morne]

1/32
2/16
2/8
2/6

all black

2/4
1/4

fine

[Zdravko.Keremidchiev]

It will be very helpful for us if you send us your scene for testing purposes.
Also as soon as we fix this issue we will let you know.

[Vizioen]

It will be very helpful for us if you send us your scene for testing purposes.
Also as soon as we fix this issue we will let you know.

I don't know if it's related but I had similar issues; Loading a previous VrayHistory file with Lens effects enabled resulted in a black image after it displayed for a few seconds. I'm 100% positive it's LensEffects related. I only had it a few times though.

[Morne]

It will be very helpful for us if you send us your scene for testing purposes.
Also as soon as we fix this issue we will let you know.

I'll see if I can post or email a stripped down scene a bit later today.
In the meantime I will attempt to add the lens effects the old way by adding vray lens effects in the max effects

[Morne]

I have some more useful info I think.

I tried various combinations of the lens effects on:
image only
image and render element
render element only

If I set both the glare and the bloom to render element (even after the fact that it turned black) then the render returns to normal, but obviously now the beauty does not contain the effect and I'm left with a useless bloom only and glare only element (which is black)

Here's the kicker however. I isolated various objects to see if it is maybe an object causing this.
Turns out that on the frames where the blank blackness appear, there are a handful of negative floating point pixels.
Here's a zoomed screengrab of the negative pixels just before the frame turns black:


This is on a max hair fur object with the built in material parameters.

I tried to add a VRayHairMtl into the mr Shader slot, but couldnt get the same look and feel as the built in paramaters. The VRayHairMtl also resulted in 25% longer render times. It did however remove the negative pixels and the glare and bloom worked as expected. This doesnt help however as the VRayHairMtl looks flat on this particular setup.

So as far as I can tell, if we can somehow clamp the black wormhole negative floating numbers at 0, it will stop the molucules from being sucked out of my image and we will be good to go?

[vlado]

Ok, I see. Did you send us the scene so that I can fix this?

Best regards,
Vlado

[Morne]

Ok, I see. Did you send us the scene so that I can fix this?

Best regards,
Vlado

Yes I've just sent an email with the subject "Lens Effects Negative Float Black Image" to
vlado@chaosgroup.com
as well as
support@chaosgroup.com

I also included some more info in the email.

[Morne]

Did you guys receive my email with the scene attached to it?

[Zdravko.Keremidchiev]

Yes, we received the scene.
The issue is on the "to do" list.