Author Topic: Too strong reflections? (Example attached)  (Read 1907 times)

2018-02-17, 10:57:47

mantaskava

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For some time now I had a feeling that some of the reflections looked too strong looking at an angle.
You can see in my example attached there is two materials (black is sRGB 50 and white is sRGB 218. Both set at reflection level 1 / reflection color 255 / Refl.Rough. 0.5 / PBR mode on.
Now looking straight at a black cube it looks totally matte, yet it still reflects so much of the white on the side. It just doesn't feel right to me. IMO such a matte looking material shouldn't reflect that much.
Am I missing something here?

Also, do you guys all use PBR mode now and don't touch reflection level and reflection color settings at all?

Thanks!

2018-02-17, 11:29:14
Reply #1

Juraj

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I would say it looks ok. I wouldn't even call that matte but rather 'satin'. And 0.5 roughness is far from matte :- ). My matte paint is in 0.2-0.3 range.
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2018-02-17, 12:32:15
Reply #2

mantaskava

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I would say it looks ok. I wouldn't even call that matte but rather 'satin'. And 0.5 roughness is far from matte :- ). My matte paint is in 0.2-0.3 range.

Hey, Juraj! Big fan of your work here :)
What's your usual roughness value for walls/ceilings and fabrics then? or MDF for example?

Another question- how would you tackle situation like this (image attached) ?
For testing purposes pretty much all the materials are set to 0.5 refl. roughness there.
Without clipping the whites on the wall I cannot increase EV more than 2.1
LUT applied is just to add some contrast.
Lighting is Corona Sky + Sun at 0.02 intensity.
Darkest blacks at sRGB 50, Brightest whites at sRGB 218

And well it all comes down to a pretty shitty image, or too dark overall. Is there any chances to make it brighter without using any artificial lights let's say? Because I always feel like artificial lights makes my renders look flat.

Oh and shadows in the kitchen area just look really harsh and sharp. Don't like those too.

2018-02-17, 13:14:58
Reply #3

Juraj

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Two things:

This is too contrasty scene with single light source. To have it evenly bright, you simply have to use some other light source for that far right kitchen corner. A photographer would.
For example bounced light from corner behind camera,etc.. or flash pointed towards ceiling. Yup, finding a spot where it doesn't flatten image is the real challenge of our work :- ) I struggle likewise.

But if you want to keep it natural with single light source, then post-production like interior photography as well, which is mostly by boosting midtones. I use curves, directly in Corona framebuffer.
Then you can add gradient in post-production.

As I said, 0.2-0.3 for truly 'matte' paint :- ). Fabrics are almost unilately zero (unless they are pseudo "metallic" fabrics like satin).
In my opinion, fabrics require their own BRDF, 0 roughness GGX is still wrong for them but it's the best you will get. Unless we'll get custom BRDF with rim lighting (retro-reflection, like Disney's Prx).
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2018-02-17, 13:44:32
Reply #4

mantaskava

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Okay, couple more then-

1. You can see some noticeable color bleeding (red color) on white cabinets of the kitchen. Should I use ray switch material to get rid of that? In this case I also feel like there shouldn't so much color bleed in reality, but I might be wrong.
2. I wonder if there is some kind of trick to make reflective plane do it's "reflecting light" job but only that? So it is not visible or blocking light behind itself. Or is this trick only viable when placing the plane directly behind the camera?
3. I'm interested if you are using Environment overrides when using corona's sky to get more varied/interesting reflections or just leave it as it is?
4. If I use custom LUTs in corona VFB, should I use linear version or sRGB one?

Sorry for harassing you but there's so much questions in my head :)) I can't stop myself lol.

2018-02-18, 12:13:28
Reply #5

Juraj

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1.) Depends on your artistic vision. Color bleed depends a lot on type of light in reality as well. Big, broad diffused light will show it less than focused directional light.
2.) Perfectly doable using Rayswitch or Object properties unless I understand your intent wrong. You can make it invisible and not affecting/blocking GI.
3.) Depends on the architecture. If I have something big mirror-y inside then yes.
4.) sRGB.
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