Corona Rendering Black in Animation

[Otuama]

Hi all.

We have an issue that I'm finding baffling.

We're rendering an animation and frame 575 is fine but 576 onward is rendering the diffuse, reflect & refract as black.  AO etc are fine.

Frame 576 is rendering fine when in perspective mode, it just seems to be when in the camera.

The camera is not going through an object or anything like that.

Isolating an object when looking through the camera works fine but when everything is turned on it renders black.

Does anyone know why this would be? 

Thanks

Here's a recording:

[Aram Avetisyan]

This seems strange.

Does the camera have any physical size?

Can you submit the files so we have a detailed look?
Does it happen only for the specified frames, or randomly until 576 too, say at 130 or 50?

[Otuama]

Thanks for the reply.

Do you have a link for me to send this?  Can't put it on the forum

Or shall I weTransfer it and open a ticket?

[maru]

You can attach many gigabytes to our support tickets :)
https://support.chaos.com/hc/en-us/requests/new

[Otuama]

Does it happen only for the specified frames, or randomly until 576 too, say at 130 or 50?

Hi, in answer to your question, this seems to be the only shot affected. All other shots have rendered fine.

[Otuama]

You can attach many gigabytes to our support tickets :)
https://support.chaos.com/hc/en-us/requests/new

Sent, thanks

[Aram Avetisyan]

Believe it or not, the issue is in "Roof_Canopy" object (profiled trim over the window) - probably an incorrect boolean operation or Corona not being able to handle thin boolean/geometry (non-enclosed mesh).

At frame 576, camera is directly under this object (looking from top), but in frame 575 it is not, and it may make Corona misinterpret the medium of rendering, turning it to all black.

If you apply tiny shell modifier or just enclose it, the render will return back to normal.
This will surely be reported and use to even further solidify of handling of medium resolving in case of non-perfect geometry.

[Aram Avetisyan]

The issue has been resolved in the ticket.

Little specific update here:

The issue is most probably not because of the boolean/bad geometry, but that the mentioned object had volumetric scattering (CoronLegacyMtl with volume absorption).
As the object was not an enclosed mesh, Corona interpreted it as an infinite medium and rendered black.

The solution is either to enclose the mesh, either disable the volumetric absorption (it was a solid non refractive object IIRC). I would suggest doing both :)