CORONA SKY ARTIFACTS

[bango74]

Lately I am testing various types of lighting, and in the various tests I have noticed that the sky crown produces a strange artifact, I made three screen shots, in the first image with only the HDRI the image is correct, in the second and third image where it is also the sky crown can be seen, like the large pixels on the glossy lacquered material, then the reference images with the settings:

[TomG]

The usual questions - which version of C4D, which OS, which version of Corona Renderer? We pretty much need that info, whatever your question or issue :)

[bango74]

I ask for forgiveness, I integrate the question hoping to receive answers that solve the problem:
-Cinema 4d r21version
-windows 10
-Corona version 5.0

[TomG]

So, some follow up questions.

- Do you have any environment overrides for Reflection or Refraction in the Render Settings -> Scene environment tab?
- If using an HDRI for the environment, does it have "Only visible in reflections" enabled?
- Is the Adaptive light solver enabled under the Render Settings -> Performance settings tab?
- Under Developmental/Experimental stuff, scroll down to Lights, and let us know what the Solver is set to there please


Thanks!
   Tom

EDIT - or you could send the scene via private uploader which would let us look at those things ourselves of course :)

[maru]

My bet would be the adaptive light solver, but I am not sure where to look for it in C4D.

[TomG]

Now that I have a little bit of time, here are some handy dandy screen grabs of where to find those various things we'd need to know about (sending in the scene is still the easiest ;) )

[bango74]

Forgive me for the delay in replying but with what is happening around the world everything has suddenly become complicated and is very time consuming, returning to the problem exposed by me I think I will share the file, unfortunately I have to clean it almost completely leaving only the elements affected for various reasons, both in size and in authorizations that I do not have for the work in question.
Could you please give me a link to get to the upload page, thanks.

[TomG]

Private uploader is at https://corona-renderer.com/upload - it's also linked to from the handy https://help.c4d.corona-renderer.com/support/solutions/articles/12000033461-how-to-report-issues-c4d page (which is linked to from my signature, to be handily available on all my posts :) )

[bango74]

Thanks for the assistance, I just uploaded the file, I'm waiting for you to verify it, good evening.

[TomG]

Yep, it's there, ty :)

[BatRM]

I don't know if it's related but i had similar artifacts  a few versions ago when i was  using corona bitmap in my HDRI on large renders.
It seemed that the HDRI became super pixelated with corona bitmap and thus producineg those artifacts.
I resolved it by using the classic c4d bitmap and filter to tweak the HDRI a bit and the problem dispeared.

[TomG]

Quick check, and it's this one "- Is the Adaptive light solver enabled under the Render Settings -> Performance settings tab?", or the first image in the three I posted above (added here too for ease)

You can disable that to remove the squares. The cause is having reflection overrides in the scene, combined with the Adaptive Light Solver, a known issue, tracked under (Internal ID=474182011) and 249869411 too.

[bango74]

Thanks Tom, forgive me I misunderstood, I thought that the adaptive light solver since it is selected by default was correct to keep it selected.
So if I have not misunderstood, if I have at least two corona sky objects and in one of these I deselect refraction reflection therefore I have to deselect the adaptive light solver?
if so, in terms of quality and time, something changes by deselecting 'adaptive light solver.

[TomG]

Yes, you have it right :) It's enabled by default as it works correctly in most cases - but reflection overrides with environments is one of the cases where it runs into some problems. We are looking into it and will keep you updated once we know more about when a fix is available.

The Adaptive Light Solver is faster, so disabling it does have a slight speed penalty as regard render time, but it will avoid these artifacts in a specific case like this. The other option is to set things up not to have reflection overrides in the environments (possibilities there could be things like using non-shadowcasting non-light-emitting backplates or other geometry for the reflections to catch - using RaySwitch to ensure that backplate etc is only visible in reflections won't cause these artifacts, as they only occur with environments with reflection overrides). Hope this helps!

[bango74]

Ok Tom, all clear, thanks for the assistance, good day