# CORONA SKY ARTIFACTS **URL:** \ **Category:** General\ **Created:** [March 7, 2020, 5:05pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723 "2020-03-07T17:05:58Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![bango74](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bango74](https://forums.chaos.com/u/bango74)\ **Post date:** [March 7, 2020, 5:05pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/1 "2020-03-07T17:05:58Z")
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: ![only hdr.JPG](https://europe1.discourse-cdn.com/chaosprd/original/3X/9/8/981c5f4accb76598444f8c1f267e8f124d820f8a.jpeg) ![only corona sky.JPG](https://europe1.discourse-cdn.com/chaosprd/original/3X/0/a/0a8afc59dcc9058512d339739acf562782639fb2.jpeg) ![corona sky+hdri.JPG](https://europe1.discourse-cdn.com/chaosprd/original/3X/5/3/53df34c352046c879a16def21bc6ed4e2903b9ea.jpeg) ![sett hdri.JPG](https://europe1.discourse-cdn.com/chaosprd/original/3X/5/7/570540e1864ec79577a8220abdedd8b860cc8a3c.jpeg) ![sett. corona sky.JPG](https://europe1.discourse-cdn.com/chaosprd/original/3X/e/e/ee5d903d624b9a7a193f861964290f24d11b45e5.jpeg) ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 9, 2020, 1:41pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/2 "2020-03-09T13:41:10Z")
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 😃 ---
**Author:** ![bango74](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bango74](https://forums.chaos.com/u/bango74)\ **Post date:** [March 9, 2020, 10:57pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/3 "2020-03-09T22:57:00Z")
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 ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 10, 2020, 3:47pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/4 "2020-03-10T15:47:37Z")
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 😃 ---
**Author:** ![maru](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/maru/32/15975_2.png) [@maru](https://forums.chaos.com/u/maru)\ **Post date:** [March 10, 2020, 4:46pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/5 "2020-03-10T16:46:53Z")
My bet would be the adaptive light solver, but I am not sure where to look for it in C4D. ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 10, 2020, 5:04pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/6 "2020-03-10T17:04:54Z")
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 😉 ) ![C4D Adaptive Light Solver.jpg](https://europe1.discourse-cdn.com/chaosprd/original/3X/b/d/bd0ae955c1aab019db1feb81c411c8fe526d91fb.jpeg) ![C4D Light Solver Devel Experimental.jpg](https://europe1.discourse-cdn.com/chaosprd/original/3X/4/5/45b5c3dd4ec16e313549aea08b574fbcbcb125e8.jpeg) ![C4D Overrides.jpg](https://europe1.discourse-cdn.com/chaosprd/original/3X/8/7/8791be033eb74964101bdae19b40eec30cfea6c1.jpeg) ---
**Author:** ![bango74](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bango74](https://forums.chaos.com/u/bango74)\ **Post date:** [March 11, 2020, 11:11pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/7 "2020-03-11T23:11:34Z")
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. ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 12, 2020, 12:47pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/8 "2020-03-12T12:47:18Z")
Private uploader is at [Chaos](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](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 😃 ) ---
**Author:** ![bango74](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bango74](https://forums.chaos.com/u/bango74)\ **Post date:** [March 12, 2020, 8:01pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/9 "2020-03-12T20:01:14Z")
Thanks for the assistance, I just uploaded the file, I’m waiting for you to verify it, good evening. ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 12, 2020, 10:26pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/10 "2020-03-12T22:26:22Z")
Yep, it’s there, ty 😃 ---
**Author:** ![BatRM](https://avatars.discourse-cdn.com/v4/letter/b/7cd45c/32.png) [@BatRM](https://forums.chaos.com/u/BatRM)\ **Post date:** [March 13, 2020, 3:10am UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/11 "2020-03-13T03:10:21Z")
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. ![artifacts.jpg](https://europe1.discourse-cdn.com/chaosprd/original/3X/6/2/62ce22df7b178e13da443ef7b4c8aeed7e7b2b4c.jpeg) ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 13, 2020, 1:02pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/12 "2020-03-13T13:02:34Z")
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. ![C4D Adaptive Light Solver.jpg](https://europe1.discourse-cdn.com/chaosprd/original/3X/b/d/bd0ae955c1aab019db1feb81c411c8fe526d91fb.jpeg) ---
**Author:** ![bango74](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bango74](https://forums.chaos.com/u/bango74)\ **Post date:** [March 13, 2020, 1:28pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/13 "2020-03-13T13:28:43Z")
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. ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 13, 2020, 1:35pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/14 "2020-03-13T13:35:18Z")
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! ---
**Author:** ![bango74](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bango74](https://forums.chaos.com/u/bango74)\ **Post date:** [March 13, 2020, 1:39pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/15 "2020-03-13T13:39:22Z")
Ok Tom, all clear, thanks for the assistance, good day ---
**Author:** ![tom\_grimes](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/tom_grimes/32/52842_2.png) [@tom\_grimes](https://forums.chaos.com/u/tom_grimes)\ **Post date:** [March 13, 2020, 1:49pm UTC](https://forums.chaos.com/t/corona-sky-artifacts/146723/16 "2020-03-13T13:49:52Z")
Most welcome! We’ve stored a link to this thread in our bug fixing tasks, so we know to come back here and update you when there is news on the fix.