Corona Renderer Forum

General Category => I need help => Topic started by: iLEZ on 2015-07-02, 09:59:52

Title: General question about very glossy refractions vs. speed
Post by: iLEZ on 2015-07-02, 09:59:52
Hello! I am working on a shot with glowing bluetooth speakers. They are lit up from the inside with an intense spherical corona light.
Does the intensity of the light and the low refraction (0.1) of the material contribute to the "noisy" results?
After 600 passes on 1250px resolution there are still noisy parts from the refracted light and on the surface of the speakers themselves. Can I construct this material some other way with similar results but less noise?
Thanks. =)
Title: Re: General question about very glossy refractions vs. speed
Post by: Frood on 2015-07-02, 11:26:31
Do you need refractions for some reason? I´d use translucency only if not.

Good luck!

Title: Re: General question about very glossy refractions vs. speed
Post by: maru on 2015-07-02, 12:47:23
Frood is probably right.
Another idea: the noise could be actually (or partially) caused by reflection. Is it still so noisy if you disable reflectivity?
Title: Re: General question about very glossy refractions vs. speed
Post by: iLEZ on 2015-07-02, 13:36:01
Do you need refractions for some reason? I´d use translucency only if not.

Good luck!

Thanks for the quick reply!
Well, I'll certainly try it with a translucent material, and we'll see if it is as realistic as the glossy transparent one. I'll post when I've tried it. =)
Title: Re: General question about very glossy refractions vs. speed
Post by: iLEZ on 2015-07-03, 08:02:30
Do you need refractions for some reason? I´d use translucency only if not.

Good luck!

I tried it, and I think it is a bit quicker. Although I get some undesired self-shadow casting inside the object. I let it run for 140+ passes. I assume that I can't use translucency on "thick" objects, so I disabled my shell modifier. I think I mix up Vray and Corona a bit, because you CAN use translucency on "thick" objects in Corona, right? I'll try that too.
I also rendered the scene with glossy refraction again but with different values and got a pretty good result with some camera raw editing.



Title: Re: General question about very glossy refractions vs. speed
Post by: iLEZ on 2015-07-03, 09:06:03
Frood is probably right.
Another idea: the noise could be actually (or partially) caused by reflection. Is it still so noisy if you disable reflectivity?

Thanks, I just tried to disable ALL reflections, but no luck, still a bit noisy. Good idea though. Perhaps I should just accept that the scene is a bit hard to render because the mail source of light is refracted/transluced(?) through a material. I made another attempt with a translucent material on a "thick" plastic. (2mm). This also has white absorbtion set to 10mm, and white scattering. I appreciate that the surface reflections show up clearly when using translucency. On the left side of the green speaker on top for example. I think this is perhaps the most realistic way to do it. 279 passes this time, at 1k rez.

(I'm *really* hoping for a native region render in the Corona VFB in future releases! :D)
Title: Re: General question about very glossy refractions vs. speed
Post by: Ondra on 2015-07-03, 09:20:16
(I'm *really* hoping for a native region render in the Corona VFB in future releases! :D)

me too ;)
Title: Re: General question about very glossy refractions vs. speed
Post by: Frood on 2015-07-03, 10:46:59
you CAN use translucency on "thick" objects in Corona, right? I'll try that too.

Yes, right. And it looks more realistic/interesting so I wouldn´t deactivate the shell mod. What´s that background in your scene? Maybe something other is causing the noise (background/floor material) - I would tweak/test in a neutral environment.

The attached scene (for further testing if you or someone else wants to) is pretty clean after 150 passes / 1k. I even activated reflection on the floor and on the cubes material.

Good Luck!
Title: Re: General question about very glossy refractions vs. speed
Post by: maru on 2015-07-03, 11:05:32
I think to get the most realistic result you would need to use SSS here. :)
Title: Re: General question about very glossy refractions vs. speed
Post by: iLEZ on 2015-07-03, 11:15:03
you CAN use translucency on "thick" objects in Corona, right? I'll try that too.

Yes, right. And it looks more realistic/interesting so I wouldn´t deactivate the shell mod. What´s that background in your scene? Maybe something other is causing the noise (background/floor material) - I would tweak/test in a neutral environment.

The attached scene (for further testing if you or someone else wants to) is pretty clean after 150 passes / 1k. I even activated reflection on the floor and on the cubes material.

Good Luck!

Excellent! Thanks for all the help! I'll try it in a neutral environment, but right now in my interative window the environment is *really* clean after 2500 passes, and the cubes and the immediate light from the cubes on the wood floor is still very noisy, so I suspect the material. =) I'll try a complete reset of the scene, and a neutral environment, maybe I've screwed up in some unexpected way.
Title: Re: General question about very glossy refractions vs. speed
Post by: maru on 2015-07-03, 11:40:32
Showing render settings could help too as I think 250 passes might be too much for this scene, I would suggest increasing GIvsAA (to 32 maybe?) and/or LSM, the result of this would be:
-better GI, glossy reflections/refractions in the same render time
-less passes in the same render time = worse AA quality, but it should not have much impact here

Also these might be helpful:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516731
https://coronarenderer.freshdesk.com/support/solutions/articles/5000526159
https://coronarenderer.freshdesk.com/support/solutions/articles/5000515640
Title: Re: General question about very glossy refractions vs. speed
Post by: iLEZ on 2015-07-03, 14:34:23
Just replying before leaving work, with a comparison between the different GI vs. AA and LSM settings:
Title: Re: General question about very glossy refractions vs. speed
Post by: romullus on 2015-07-03, 15:50:10
Your comparison is not valid because you're tested with fixed passes when you should test with fixed time.
Title: Re: General question about very glossy refractions vs. speed
Post by: maru on 2015-07-03, 16:21:07
Your comparison is not valid because you're tested with fixed passes when you should test with fixed time.
I don't see anything bad in checking with fixed passes, but it looks like they are not even fixed here. :)
Title: Re: General question about very glossy refractions vs. speed
Post by: iLEZ on 2015-07-03, 23:34:56
I dumb. :D

I'll do a proper like-for-like test on monday, I can't even begin to explain what went wrong with this test! :)