Corona 10 HF2 - pitch black screen both when previewing and rendering.

[TC]

Hi,
Decided to make another attempt at installing ll CR10 HF2 efter previously being forced to revert to 9 because of issues with some of my scenes suddenly not opening in 10 (the loading assets issue that few others also reported)
A previous scene rendered perfectly fine with Corona 9 this morning. After the installation of 10 HF2 the interactive screen is pitch black, and so is the render.
No changes whatsoever to lighting, secondary solver or camera settings. The exact same scene.

Already read previously reported similar issues and i can not identify the issue in my case. On a side note : I am legitimately wondering as to why am I forced to revert to 9 again to finish my work (my previously reported issue with 10 did not get any answer or solution), and still paying subscription for a later version that does not work (second issue with 10 in two months now, been holding onto that reliable 9-version for my dear life)

Help would be greatly appreciated.

Regards
TC

[TomG]

If you open a ticket for this problem with the latest scene you tried, and sent in a copy of the scene, that would be most helpful - https://support.chaos.com/requests/new

The only known change in 10 that can make a scene render black is if an object that uses some volumetric shading is not an enclosed 3D object, e.g. is a flat plane for a wall or ceiling. Due to the camera calculating whether it is inside a volume or not, any non-enclosed objects will be considered "infinite" in terms of their volume, so that is what I would check. Planes for walls, ceilings, or anything else, are generally not recommended anyway, as everything should be built physically realistically for best results and everything in the real world has some sort of volume.

Let us know if that resolves the issue. You could test quickly by using material overrides to replace all the materials in the scene and see if everything renders as expected then, and then it would be a case of hiding half the scene objects (without mat overrides), seeing if it renders; if black, hide another half of that half, and so on, until the problematic objects are identified.

PS - where is the previously reported issue, please? Thanks!

[Avi]

Hi,

just trying to do a follow-up on your issue. Did you raise a ticket for your issue yet?

You can send a ticket to us using this link: https://support.chaos.com/hc/en-us/requests/new

[TC]

If you open a ticket for this problem with the latest scene you tried, and sent in a copy of the scene, that would be most helpful - https://support.chaos.com/requests/new

The only known change in 10 that can make a scene render black is if an object that uses some volumetric shading is not an enclosed 3D object, e.g. is a flat plane for a wall or ceiling. Due to the camera calculating whether it is inside a volume or not, any non-enclosed objects will be considered "infinite" in terms of their volume, so that is what I would check. Planes for walls, ceilings, or anything else, are generally not recommended anyway, as everything should be built physically realistically for best results and everything in the real world has some sort of volume.

Let us know if that resolves the issue. You could test quickly by using material overrides to replace all the materials in the scene and see if everything renders as expected then, and then it would be a case of hiding half the scene objects (without mat overrides), seeing if it renders; if black, hide another half of that half, and so on, until the problematic objects are identified.

PS - where is the previously reported issue, please? Thanks!

Just opened a ticket.
Rendering with a white override-material works just fine. The regular render, on the other hand, is black. Just installed the 11 RC1, same behaviour on a 9-scene that rendered perfectly.

My previous report is within a thread reporting slow asset loading times. That was when I had to revert to 9 to get the work done.

[TomG]

With the override being fine, it does sound even more like a case of a material with volume settings applied to a non-enclosed piece of geometry. If so, hiding objects should uncover the culprit, you can do that by halves, and half again, until the object with the material is tracked down (unless you happen to know that there is some volumetric setting used someplace, or there is only one ceiling that has no thickness, etc. :) )

[TC]

OK, thanks.
I must admit though I am very confused as to why 2D-geometry (with no thickness) has become a problem with newer Corona-versions.
For instance, even if I model a ceiling object (I use Sketchup for most of my modelling, did so for the last 15 years), it is very common that the underside of the ceiling has different material than the rest of the ceiling object, which often translates into that face being an object/mesh, the rest of the ceiling another object/mesh and so on. Always been like this. So this can not possibly be the issue, all of a sudden. An outer wall usually has three or more different materials, for instance, they usually get separated into meshes to make for easier UVW-mapping and so on.

Also, there are absolutely no material with volume settings in this scene, not that I know of.

[maru]

Wait a sec, I will prepare a script for you which will clear any volumetric effects from all materials in your scene.

[maru]

Ok, just drag and drop this into the viewport and try re-rendering. It would be best to save a backup of your scene in case it messes up some materials which should have volumetric effects enabled in them. :)

[TC]

Thank you for the script.
Tried it just now and unfortunately it has no effect on the scene, still a black screen. But it might come in handy for others with volumetric materials in the scene.

Like I said, nothing like that in mine.

If I revert to 9, it renders just fine.

[maru]

Interesting. In that case, we will investigate through the ticket #175932 you have submitted.

[TC]

I guess I should submit the scene as well. I did not attach the scene to my ticket.
Should the assets in the scene (like textures, hdri maps) be sent to you as well?

[maru]

Yes please, that would be best.

[TC]

Just did that.

[TomG]

"I am very confused as to why 2D-geometry (with no thickness) has become a problem with newer Corona-versions."

As noted, this is because cameras now decide whether they are inside a volumetric object, to allow cameras to be half submerged in water, or fly through clouds and smoke, etc. This was introduced in Corona 10. Some materials, e.g. marble, may be set up with some Volumetric Scattering inside the Media Options settings. 2D objects are only a problem when this type of volumetric effect exists, because Corona has no way to know where the volume ends with a 2D object as the volume is not enclosed at all, and so it determines that the camera is inside the volume and renders accordingly.

BTW if the wall is a cube with this material with volume settings applied to one face, as you describe, then Corona treats the cube as defining the scope of the volume and there is no problem (unless you were inside the wall anyway ;) ). It only happens with e.g. a plane or other shape that really has no enclosing volume.

[Avi]

Just an update here:

The above script didn't work because it was targeting Corona physical material in the scene though we assume that users should always be using Corona physical material as the new standard when rendering with Corona but in this case, the user was using 3ds Max native Physical material with SSS applied to walls and ceiling.

Here is a script to turn off SSS from all physical material in the scene at once.

Code: [Select]

for mat in scenematerials do
(

if classof mat == PhysicalMaterial then
(

mat.sss_depth = 0.0

mat.sss_scale = 0.0
)
)
 

print "SSS Depth and Scale set to 0 for all Physical Materials in the scene.
I hope this helps.

[maru]

The above script was targeting both Corona Physical Mtl and Corona Legacy Mtl, but I didn't think of the Autodesk Physical Mtl, thanks. :)