Author Topic: Corona 0.41 (Maya 2016)  (Read 27382 times)

2015-05-20, 21:47:39

Eian

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Hey Haggi,

Well done on your last release. Areal lights working properly now.
Though when I connect a texture to a to a surface through coronaLight material, I still get strange results as you can see on the image attached.
Problem occurs in progressive and bucket rendering mode as well.

Another thing I noticed with Maya 2016 is that if I save a rendered image as an openexr it wont save its gamma settings correctly.
That applies regardless of the color management setting under Maya's preferences.
Now this might be a Maya problem cause it happens with other renderer as well but I believe there might be a way you can fix it.
Only workaround I found working, is to change Colormapping_gamma to 1.000 and then save the image. And btw saving raw / color managed mode does the same thing.
So even if this is a maya problem maybe you can force a Colormapping_gamma of 1.000 just before saving the openexr image?

As you pointed out CoronaVFB is really experimental at this stage and due to constant crashes I can't say much as of now.

Keep up the good work!

Regards,
Ian

2015-05-21, 10:17:14
Reply #1

haggi

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Could you please clarify the exr problem a bit?
Do you save the rendered image directly from the renderview? Or do you mean the automatically saved image from rendering which can be found in the images directory? The rendered image will always be saved in the images directory. And if it is an exr, color correction is used, but gamma will be set to 1.0.

The image in the renderview contains gamma from color mapping. I will change the default settings for maya2016 so that by default in a new scene the gamma will be set to 1.0 what should be better because by default Mayas ColorManagement is turned on.

At the moment there is no way to save a raw - non color mapped image (except gamma). But it should be possible to implement it if needed.

2015-05-21, 18:17:14
Reply #2

Eian

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Oh I forgot to check the image output through the render settings and now that I did I see that it works just fine!

So the problem only occurs when saving through the renderview!
Though I wouldn't recommend you changing the default colormapping_gamma to 1.000 cause it will affect the quality of the rendered image which makes sense cause when a lower gamma is used the renderer will not refine the darkest areas. So when you apply the correct gamma of 2.2 you will get more noise in the darker areas.

As of now by turning off maya color management and saving through the render settings works fine.

Regards,
Ian

2015-05-22, 00:17:45
Reply #3

haggi

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Gamma does not affect the quality of the rendered image. I simply want to avoid double gamma in maya2016 what is the case if you use color management in maya what will be the default because is simply gives better results.

2015-05-22, 19:47:57
Reply #4

Eian

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Hey Haggi,

I understand you want to avoid double gamma correction and seemingly it comes to your preference what the default settings will be, they can be changed anyway.

Generally speaking, I won't post something before I test and as shown in the images attached, gamma setting (when chosen through the render settings) affects quality of the image, sometimes less sometimes more depending on the lighting.
V-ray has a setting for that as well, called "adaptation only" which allows the renderer to proceed with all its calculations as though color mapping is applied without applying color mapping so that the noise levels can be corrected accordingly.

In the images attached the one rendered with a gamma of 2.2 has less noise and was done in less time even though all the other settings were identical.
The image named "Gamma 1.0 to 2.2" is identical to the first one which was rendered with a gamma value of 1.0 and then corrected to 2.2 in post.
Difference might be small but is surely there.

Regards,
Ian

2015-05-25, 14:46:03
Reply #5

haggi

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In Corona the color mapping settings have no influence at all on the rendering process. The image is rendered and then after rendering the color mapping including gamma are applied to the framebuffer. So all noise or other elements you see in the image with gamma 2.2 are already in the image with gamma 1.0 but they are less visible because they are darker. So if you need to adjust the image quality, then you simply apply the appropriate gamma (2.2 in Maya2015 without mayas color management) and do the rendersettings in a way quality is good enough.

2015-05-25, 18:12:42
Reply #6

Ondra

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actually some parameters (like MSI) are influenced by the initial exposure value, so you should not change exposure much after you start rendering
Rendering is magic.How to get minidumps for crashed/frozen 3ds Max | Sorry for short replies, brief responses = more time to develop Corona ;)

2015-05-25, 19:21:28
Reply #7

Eian

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Thank you Ondra.

I can understand haggi's misunderstanding on the subject, because theoretically gamma is applied after the rendering process but in reality it seems this is not the case as you just explained.

Attached is a better example to show the difference. Again in one image gamma correction is applied after the rendering, and on the other before the rendering.
I must also note that I'm using bucket renderer to better illustrate the difference because supposedly progressive mode doesn't use adaptation as much hence the result should be similar.
All the other settings apart from Colormapping_gamma are identical.

Kind regards,
Ian
« Last Edit: 2015-05-25, 19:42:45 by Eian »

2015-05-25, 19:35:58
Reply #8

Ondra

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well gamma should not play role - just exposure ;)
Rendering is magic.How to get minidumps for crashed/frozen 3ds Max | Sorry for short replies, brief responses = more time to develop Corona ;)

2015-05-25, 19:46:44
Reply #9

Eian

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Hey Ondra,

Hmm I see but why is there a difference on the images I tested? I just changed the Colormapping_gamma setting not the exposure.
Could it be that the Colormapping_gamma setting is somehow unintentionally related to exposure?
« Last Edit: 2015-05-25, 19:51:16 by Eian »

2015-05-25, 19:57:03
Reply #10

haggi

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Could you please send me this scene? I just tried to reproduce the effect with one of my more complex scenes and the images were identical.

2015-05-25, 20:18:53
Reply #11

Eian

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Hey Haggi sure!

Btw are you using bucket mode? As I said on my last post due to the fact that progressive mode does not use adaptation refining methods (Adaptive Threshold), the results should be the same if not identical when using progressive mode.

So my initial point was that the "thinking" of the renderer gets affected by the Colormapping_gamma setting whether that should happen or not.
You just have to use certain settings in order to see it though :).

Attached is the scene.

2015-05-27, 00:00:02
Reply #12

haggi

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Okay, you are right. I tested it in maya2015 and there is a difference. If I set the gamma before rendering, rendertime is 3:18min. Setting it after rendering results in more noise and a rendertime of 1:55min. But I did not get any difference in brightness which appear in your images.

2015-05-27, 00:44:34
Reply #13

Eian

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Hey Haggi,

There is no brightness difference in my images either.
Bottom images might seem brighter due to the viewing angle of your monitor. If you download them and open them sequentially you will see no difference in brightness ;)
Anyhow no problem with exr gamma if I use the image saved through the render settings.

Any progress on the texture lighting issue? It would be great if you could fix in your next release! :)

Kind regards,
Ian

2015-05-27, 09:41:03
Reply #14

haggi

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Sorry, still no idea what's happening with textured lights at the moment.