Images rendering with rectangular irregularities

[jamieirvin]

Hi,

My colleague has been rendering a scene recently and has noticed some sections of the image render 'differently'.  There are rectangular areas throughout the final image that look lighter than the rest of the image.  It's best described as looking like a number of areas have been region rendered for a while and then the regions were disabled whilst continuing the render, resulting in an image with overall noise of 10% and localised 'regions' at 4%.... However, no regions are active and the image was rendered over a period of 2 hours.

The scene has been stripped of any environment fog, trees, bushes, cars, people etc so it is light weight and the issue persists.  We have imported the geometry and lighting in to a new scene and used new render settings, yet the issue persists. It has also happened on a second, completely new scene model with all new lighting and render settings.  So it is not an isolated incident.

We are now testing the scene in other C4D version installations and on different machines to see what happens. 

However, I thought I would ask the question here as someone may have come across a similar issue before.  I'm hoping it is an easy fix and something we have simply overlooked...

Thanks

[NOOKTA]

Hi there,

just a few things to rule out:

• flipped normals
• phong tag
• try override material
• move camera slightly to see whether the weird rectangles move as well or stay at the same part of the building

Best,
Ararat

[Beanzvision]

Were these models created within Cinema or imported from elsewhere? As already mentioned, please check the phong tag. If the above steps do not help, please contact us at support and we will investigate further. We can be reached here support@corona-renderer.com

[TomG]

Some other questions for info

- Is the Adaptive Light Solver enabled (in the Performance Settings tab of the Render Settings dialog). If so, does disabling it change the result?
- What's being used for the environment lighting (HDRI, Corona Sky, multiple HDRIs or Corona Skies?)
- Are there any reflection, direct etc. overrides used (Scene Environment tab of the Render Settings dialog)

Thanks!

[BigAl3D]

Since I render a lot of models made elsewhere, usually Max, one thing I always have to do is select all the points and run the Optimize command. I find many times not all the points/seams are welded together. Also, to my eye, those boxes can't be flipped normals since they don't follow any geometry. I'm wondering if this was rendered as a still with Team Render? Almost looks like certain sectors were assigned to different CPUs and maybe, just maybe calculated slightly different lighting?

I know with C4D's Global Illumination, it's best to cache the GI first so each different CPU will use the same lighting info and prevent issues, usually flickering. OK, I'll put my dev hat away now.

[jamieirvin]

Hi all,

Thanks for your reply and thoughts on this.  It's been a real head-scratcher.  There's always something that gets the brain cells twitching on a normal day, but this has been a proper challenge!

We had a good idea that it wasn't related to phong, normals or generally related to the model geometry as it is all modelled from scratch within C4D and the error wasn't consistent with mesh errors due to the very rectangular and overlapping nature of the areas in question. 

However, when we shifted the camera and removed all the textures from the scene, the problem persisted. I eventually ended up collapsing the entire scene in to two meshes and removed all tags.  I was left with a bare mesh, a light and a camera.  And then I noticed it...!  When we prepare photo montages, we add a 'background' object as the child of the camera.  This has the backplate mapped on and in our default scene we have a Python Tag that controls the visibility and render-ability of the backplate. When the camera is used, the background becomes visible but, crucially, is not renderable (see attached). This a solid tried-and-tested way of working with numerous backplates in a single scene and something we use daily.  However, in this instance, the artist in question removed the Python Tag and the 'background' object 'traffic lights' were grey, so Corona was attempting to render it.  As far as I understand, the background object isn't supported / recognised by Corona and therefore it just became an annoying interference that made a right mess of the render output!

Anyway, to cut a long story short... we fixed the issue and will be keeping an eye on "Artist X' to make sure he doesn't ruin my day again.

Thanks again for your responses and apologies to the Corona Team for possibly insinuating that your beautiful software may be to blame... 😳

[Beanzvision]

Hi Jamie, Glad to hear you were able to sort it out. May I also ask what version of Corona you are using? The background object is now supported in the latest release.

[jamieirvin]

Hi,

I'm running Version: 5 hotfix 2 on one machine and version 6.0 on another. 

Which version now supports backplate?

(edit) I've just updated to Version 6 HF2 and the backplate issue still occurs. I've not tried Version 7 dailies ... yet

[jamieirvin]

As a side note, In all today's testing across numerous machines, we found that scenes saved in C4D R21 using Corona Version 6 wouldn't open in R21 using Corona Version 5. We would get the following error (see attached).

We have since updated the machines that run Version 5 to now run Version 6 and all the Cinema4D files now open just fine.  Again, this took a while to sort so I thought I'd mention it here as I am sure I won't be the only person that may come across this issue in the future.

In the interest of being thorough, we duplicated the Cinema installation on a machine so we could run two identical versions of the application in parallel.  We confirmed our above findings that scenes created in Corona Version 6 are not backwards compatible (at least with version 5).

I have no idea why this is the case... but I'm glad we have found the issue.

[TomG]

Correct, Corona 6 brought changes to the node editor etc. which means scenes saved in it cannot be opened in Corona 5. It was in the release blog at https://blog.corona-renderer.com/corona-renderer-6-for-cinema-4d-released/

PLEASE NOTE: Because the new node system saves data in a different format, if you save a scene using Corona Renderer 6, you will not be able to load and use it in earlier versions of Corona Renderer.

[jamieirvin]

ah... I missed that note 😂

Thanks for the info and I'll keep that in mind! 👍🏼

[NOOKTA]

Correct, Corona 6 brought changes to the node editor etc. which means scenes saved in it cannot be opened in Corona 5. It was in the release blog at https://blog.corona-renderer.com/corona-renderer-6-for-cinema-4d-released/

PLEASE NOTE: Because the new node system saves data in a different format, if you save a scene using Corona Renderer 6, you will not be able to load and use it in earlier versions of Corona Renderer.

I'm sure a lot of people may have missed that note - including me. Why don't you add an info to the error message pointing towards the issue of having different corona versions?? I recently spent two hours figuring that one out.