Glass reflection

larszzz · 28 Sept 2014, 19:45

Hi everyone. I have a question. I'm trying to get the reflection of a sky bitmap in my glass-windows. I have tried this to import a sky bitmap into my environment GI and BG and my glasses have a fresnel of 1,55. But nothing happens in my render

What am i doing wrong?

Thanks,
Lars

TedVitale_CG · 30 Sept 2014, 12:13

Hi Lars,

Try bumping the Fresnel reflections up to 3.0. Fresnel controls how reflective things are, so metallic items start at about 10-20 and range up to 60. If I'm making a mirror Ill go all the way to 80 with a diffuse color of dark grey or black.

Hope that helps!

eidam655 · 30 Sept 2014, 13:19

Ted,

are you sure that changing the Fresnel to ridiculous value is the real solution here?

i'd be more concerned with the environment settings and their multipliers, and also the lighting used.

larszzz, if you posted a screenshot (of the render and/or environment settings), that would be immensely helpful.

andybot · 30 Sept 2014, 14:54

I sometimes bump up my fresnel ior to get the proper looking amount of reflection in my glass, especially if nothing is behind it, usually 2.5. But it only works if the environment is correctly set up. It's hard to know without an image from the OP.

BTW, for a mirror, it's much simpler to change from Fresnel reflection type to "none" - then you can adjust the reflection color from white to a light gray if you want the reflection to be less strong, but still look like a mirror.

valerostudio · 30 Sept 2014, 16:57

3.0 seems like a lot. Maybe 1.8 when I am really faking it, but I would never (or need to) use 3 for Fresnel.

Are you using thick glass with refraction? Front face check? The angle are you viewing the glass at will effect how the reflection looks - that's what Fresnel is.

If you must fake a reflection, just take Fresnel map off the reflection slot and add a very dark gray, almost black color to your reflection slot. The closer to white - the more reflection.

rspierenburg · 30 Sept 2014, 19:54

Is the OP talking about IOR or the actual reflection value?

valerostudio · 1 Oct 2014, 12:58

Guess we need to see a screenshot to really see whats going on.

Sounds like they just want to see more of the BG reflected in their glass. Most of us would achieve this by upping the IOR. My suggestion as a cheat is to not use Fresnel at all (I know, blasphemy).

larszzz · 1 Oct 2014, 17:31

Hi guys,

Sorry for my late reply, but i was expecting a mail for replies.

So anyway, i posted a screenshot from my render and screenshots from my environment settings. I hope this will help

Btw, my bitmap picture is a light blue sky with white clouds...

Thanks,
Lars

larszzz · 1 Oct 2014, 17:35

Forgot my settings screenshot

rspierenburg · 2 Oct 2014, 11:35

So from what I believe I see, its not the reflection that is the issue. It looks as if something is going on with your background. Could you post a copy of the background-hd-20.jpg? I'm just curious as to what is was supposed to look like.

Rob

andybot · 2 Oct 2014, 12:17

you need your mapping to be "UVWGenEnvironment" instead of Channel.

valerostudio · 2 Oct 2014, 12:24

If you upgrade to 2.0 you will have domelight and a bunch of bug fixes.

larszzz · 2 Oct 2014, 14:56

Okay, i have changed my mapping (channel) into Environment. Now i can see my sky in the bakground, but it's way too dark. And my windows aren't really reflecting it

I have to import the bitmap into GI and BG, right?

I post here my bitmap picture and my new render

Lars

valerostudio · 2 Oct 2014, 16:04

1- Thats not a 360 sky - Google 360 sky image

or

2- Use any of the free HDRI skies on the web
http://www.cgarchitect.com/news/viewframe/free-360-sky-panoramas-from-viz-people

if you use a JPEG, you have to switch the color space of the map to sRGB

Play with the intensity values. It might need to be .1, 1.0, or as high as 30 - depends on the file.

larszzz · 3 Oct 2014, 07:59

Thanks already for your help!
I have tried to play with some values but my sky stays very dark. Where can i find the intensity value of my sky?

I post here my new sky jpeg, my settings for GI color and BG color, and my render.

Gr Lars

larszzz · 3 Oct 2014, 08:02

My screenshots

numerobis · 3 Oct 2014, 08:31

you should better try with a HDRI instead of JPG...

http://www.viz-people.com/portfolio/free-hdri-maps/

larszzz · 3 Oct 2014, 09:36

I now used a HDRI, wich looks better, but it stays very dark. Do you guys use a rectangle light in the scene to get it more brighter? Or where can I change my light settings in the options editor? I'm used to change my light settings only in environment, right? But as long i use a bitmap instead of texsky (sunlight), it stays dark. Is there another option of changing the light AND using a bitmap?

Thanks,
Lars

andybot · 3 Oct 2014, 10:27

nah, you need to change your camera settings. The default is very dark for anything other than default sunlight. Change shutter speed to something like 100, and aperture to something like 6.0. Keep playing with the values until you get a brighter image.

larszzz · 3 Oct 2014, 11:44

Aha nice, that was very helpfull:-) Thanks andybot!
This forum is great!