Author Topic: Stains on the image  (Read 3996 times)

2021-04-03, 16:20:55

Mettigel Hawaii

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Hello,

In February I was working on my final render for my university project. I already had threads about frosted glass material posted in the forum.
Back then I was trying to render my final image of my interior, but somehow I had big troubles. I had little time and then there were these stains in the image, which made it impossible for me to use the image. So I restarted the rendering many times, later with lower quality and resolution. I tried different things, in the end I got a low quality image, which I was not really happy about. Does anyone know whats the reason for those stains? Also I wanted to ask wheter you have general tips for me to improve my image further and also my Corona skills for the upcoming project.

Looking forward for your respond.

2021-04-04, 20:21:05
Reply #1

BigAl3D

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Are you referring to those white dots all over the area down below? If so, then I just posted in the Daily Builds section about something similar and even black dots after upgrading to the latest build. I have this issue when using the UHD Cache option. Try switching it to Path Tracing and see if it improves. If it does, then we are seeing the same problem.

Also, you should post what OS you're using, C4D version and Corona version. This helps a lot.

2021-04-05, 15:19:56
Reply #2

Mettigel Hawaii

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I am working on Windows 10Pro, Cinema 4D R23, Corona 6.

I did the rendering again with Path tracing and it's still the same with the stains.
I was thinking that maybe I did some mistakes with the materials. I was using a lot of frosted glass for the walls and I was thinking wheter the sports might be some weird reflection from the light.


2021-04-05, 15:24:09
Reply #3

TomG

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Very hard to tell just from images - any chance you could upload the scene via private uploader (be sure to either open a ticket and mention the filename uploaded in the ticket, or come back here and mention the file name) - see https://help.c4d.corona-renderer.com/support/solutions/articles/12000033461-how-to-report-issues-c4d

(BTW white dots and black dots are likely different - black dots are likely NANs, you can right click in the VFB and mouse over them to see if it gives an RGB value or whether it says NAN; a NAN is an error in the calculations in the renderer, but white dots are likely something else like reflective caustics)
Tom Grimes | chaos-corona.com
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2021-04-05, 16:36:04
Reply #4

Mettigel Hawaii

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I uploaded the file onto the dropbox link. The file name is "3D Endabgabe Architekturschule Mombasa fertig"

I can't render the file again, since it's always crashing after some time.

2021-04-05, 17:06:01
Reply #5

TomG

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So far it seems to be rendering ok here. Some questions though:

- You have multiple LightMix layers set up. There is no support for multiple LightMix layers at this time, what happens if you delete those extras and just have the one LightMix?
- I am not sure what your sample renders show in the first post - are they Beauty passes, LigthMix results? What's the difference between the first and second image, since one has those strange patterns on it, and another does not?
- No textures included with the uploaded file, not sure if that makes any difference (could be no textures are used)
- The Render Settings show the Ambient Occlusion and Global Illumination options present and enabled, but Corona doesn't use those. What happens if you delete them?
- Caustics and Sketch and Toon are included there too but not enabled - all the same, I would delete them since they are not compatible with Corona and who knows what odd effects they could be causing (worth a test to remove them!)
- Was this final render, or IR? If IR, what happens if you disabled Fast Preview Denoising?



I only had a few fireflies on some metal objects (the railings) in the "sun" LightSelect layer only.
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2021-04-05, 17:14:44
Reply #6

TomG

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(The place where I get fireflies is the mesh of the railings - this does have three materials stacked, does use texture maps that I don't have, and one of those materials is a non-Corona material, should work fine as a native C4D material, but not sure what effect the missing texture maps have on my render - or indeed if texture maps are used anywhere else that I may be missing that could cause differences).

A "Save Project with Assets" will collect scene and texture maps into a folder, which can be zipped and uploaded, to make sure we are rendering the exact same thing :)
Tom Grimes | chaos-corona.com
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2021-04-09, 16:51:59
Reply #7

Beanzvision

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Could it be that you have multiple suns and skies?
Bengamin Jerrems l chaos-corona.com
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2021-04-11, 18:43:11
Reply #8

Mettigel Hawaii

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Hi,

I uploaded it as a zipped data with the assets included. It's called mombasa endabgabe

- I had multiple light mixes and mulitple suns and light sources, because I was making different renderings in the same modell. I deactived the sun when I went from the interior to the exterior scene and activated the suns which I set up for the exterior rendering. Is there another technique? Maybe that caused troubles. I could work in different datas for different scenes, but that sounds like it would be a lot of additional work.
- Both of the pictures I was showing were Beauty passes, with different settings. Both of them have stains, one more than the other one though.
- I didn't know that Ambient Occlusion and GI are not supported. So I only have to set up Corona in rendering settings, the rest is not supported?
- I disabled Sketch and Toon and Caustics now.
- Is there something else than interactive rendering? I have only been working there. I didn't even set up a limit, I just waited after pressing render and saved the pcitrue when I was happy with the result.


Thank you guys for your answers.

2021-04-12, 14:51:26
Reply #9

TomG

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Quick note - you can have multiple suns and skies, but you still should only have one LightMix :) You do need different LightSelects for each sun and for each sky, but still only one LightMix (and within that one LightMix you can then enable / disable the relevant suns and skies as needed).
Tom Grimes | chaos-corona.com
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2021-05-08, 13:21:08
Reply #10

Konichowaa

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I often had those kind of white dots too, when using a HDR file as a visible background and typically only in direct lighting areas and on bumpy or displaced materials.

The white dots dissapear immeadiately whithout changing any settings when

i use a tonemapped bitmap (JPG/PNG) instead for the visible background+reflection+refraction+mask
  c4d sky object with tonemapped on/in it, add compositing tag and uncheck GI+shadows in the options
  OR
  when using the new corona sky object in shader/hdri mode , uncheck 'visible by GI' in the object properties)

and keep the HDRI only for GI lighting+shadows.
  c4d sky object with the HDR on it, add compositing tag and keep only GI+shadows checked in the options
  OR
  when using the new corona sky object, uncheck visible directly+refl+refr in the object properties
that worked for me
Koen Van haesendonck
3D-lab - www.3d-lab.be