frosted glass in LS?

Ernest Burden · April 29th, 2003

Frosted glass is a problem. It SHOULD be easy for a 'physically based' lighting system...yet it isn't. But that never stops me from trying...

I have a current job which is a restaurant that has a bunch of partitions made of boxed frosted glass with small lights randomly placed inside. So I did some tests:

and...

have any of you gotten any better results for frosted glass in Lightscape? I tried REALLY hard to do this without any self-illum. (real glass doesn't do that) it works, but is too dark. So this has a small amount of self-illum. While I will, in the end, make my material opaque enough to NOT see anything beyond, the test for me was to make the glass blur shapes beyond, and to blur them more with distance. I think this does that.

Ernest Burden · April 29th, 2003

A big success, and a failure, too. A try at a frosted glass on a real model shows it does indeed get more blurred with distance, but of course, acts like regular glass with sunlight raytraced as if the glass were clear.

I suppose you could put in a polygon to cover to glass area and turn it into an area light, and put it on an off layer and render with 'shadows from off layers'...but who has that much time? Speaking of time, the higher the aa setting, the more soft the blur on the frosted glass, but the render times go through the roof. This example is set at aa=6, aa=10 is much nicer, but I don't have all day. I can think of another workaround, too, but how many tricks can I teach this old dog?

Asim Harbas · April 30th, 2003

Used texture for glass with alpha canal
Alpha canal: 50% black
Glass properties:
Transparency: 0,00
Shininess: 0,54
Refractive index: 1,46

Asim

Martin Lupton · June 4th, 2003

Ernest

Can you post the settings you used for the frosted glass in teh second setting - it looks pretty good. more like textured than opal frost but good anyway.

Attached is my attempt.

Martin

Martin Lupton · June 4th, 2003

How do i insert a picture?

STRAT · June 4th, 2003

Quote:

Originally posted by Martin Lupton:
How do i insert a picture?

Martin Lupton · June 5th, 2003

thanks

Ernest Burden · June 5th, 2003

you won't like this question...which is supposed to be the frosted glass surfaces?

How quickly are you looking for the settings? I'm crazy busy.

I used a combination of bump mapping and, unfortunately, a little self-illumination. It shouldn't need that, but it does. There are different bump setting for the front and inside edge of the glass, which help to difuse the light when raytraced.

Martin Lupton · June 6th, 2003

ouch that smarts...but is also the point of my original question!!!

the white back panel is constructed of two layers of glass facing a metal back panel. linear fluorescent lamps are placed at the top aiming downwards. The close up shows this, but this was the best opal i could get on the glass.

Martin

Martin Lupton · June 6th, 2003

forgot the attachment

April 29th, 2003	#1 (permalink)
Ernest Burden Veteran Member Join Date: Apr 2002 Location: Ossining, NY USA Posts: 4,999 Name: Ernest Burden III	Frosted glass is a problem. It SHOULD be easy for a 'physically based' lighting system...yet it isn't. But that never stops me from trying... I have a current job which is a restaurant that has a bunch of partitions made of boxed frosted glass with small lights randomly placed inside. So I did some tests: and... have any of you gotten any better results for frosted glass in Lightscape? I tried REALLY hard to do this without any self-illum. (real glass doesn't do that) it works, but is too dark. So this has a small amount of self-illum. While I will, in the end, make my material opaque enough to NOT see anything beyond, the test for me was to make the glass blur shapes beyond, and to blur them more with distance. I think this does that. __________________ Ernest Burden III AcmeDigital architectural rendering

April 29th, 2003	#2 (permalink)
Ernest Burden Veteran Member Join Date: Apr 2002 Location: Ossining, NY USA Posts: 4,999 Name: Ernest Burden III	A big success, and a failure, too. A try at a frosted glass on a real model shows it does indeed get more blurred with distance, but of course, acts like regular glass with sunlight raytraced as if the glass were clear. I suppose you could put in a polygon to cover to glass area and turn it into an area light, and put it on an off layer and render with 'shadows from off layers'...but who has that much time? Speaking of time, the higher the aa setting, the more soft the blur on the frosted glass, but the render times go through the roof. This example is set at aa=6, aa=10 is much nicer, but I don't have all day. I can think of another workaround, too, but how many tricks can I teach this old dog? __________________ Ernest Burden III AcmeDigital architectural rendering

June 5th, 2003	#8 (permalink)
Ernest Burden Veteran Member Join Date: Apr 2002 Location: Ossining, NY USA Posts: 4,999 Name: Ernest Burden III	you won't like this question...which is supposed to be the frosted glass surfaces? How quickly are you looking for the settings? I'm crazy busy. I used a combination of bump mapping and, unfortunately, a little self-illumination. It shouldn't need that, but it does. There are different bump setting for the front and inside edge of the glass, which help to difuse the light when raytraced. __________________ Ernest Burden III AcmeDigital architectural rendering

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April 30th, 2003	#3 (permalink)
Asim Harbas Senior Member Join Date: Apr 2002 Location: Austria Posts: 104 Name: Asim Harbas	Used texture for glass with alpha canal Alpha canal: 50% black Glass properties: Transparency: 0,00 Shininess: 0,54 Refractive index: 1,46 Asim

June 4th, 2003	#4 (permalink)
Martin Lupton Junior Member Join Date: Jan 2003 Location: London, UK Posts: 13 Name: Martin Lupton	Ernest Can you post the settings you used for the frosted glass in teh second setting - it looks pretty good. more like textured than opal frost but good anyway. Attached is my attempt. Martin

June 4th, 2003	#5 (permalink)
Martin Lupton Junior Member Join Date: Jan 2003 Location: London, UK Posts: 13 Name: Martin Lupton	How do i insert a picture?

June 5th, 2003	#7 (permalink)
Martin Lupton Junior Member Join Date: Jan 2003 Location: London, UK Posts: 13 Name: Martin Lupton	thanks

June 6th, 2003	#9 (permalink)
Martin Lupton Junior Member Join Date: Jan 2003 Location: London, UK Posts: 13 Name: Martin Lupton	ouch that smarts...but is also the point of my original question!!! the white back panel is constructed of two layers of glass facing a metal back panel. linear fluorescent lamps are placed at the top aiming downwards. The close up shows this, but this was the best opal i could get on the glass. Martin

June 6th, 2003	#10 (permalink)
Martin Lupton Junior Member Join Date: Jan 2003 Location: London, UK Posts: 13 Name: Martin Lupton	forgot the attachment

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