Architectural glass opacity missing alpha channel

Ras · October 29th, 2004

Hi again

I´ve run into a problem with my Architectural glass and alpha channels.

It seems that when i save my image and try to use the alpha channel to map my background into the picture the glass appears as a completely opaque object?!?

I don´t know how to work aroun this problem. I have no problem when using a standard material with for example 20% opacity but Architectural glass is so much nicer...

What to do?

Ras · November 12th, 2004

Helloooooo?!?

[knock-knock] Is this thing on?

abicalho · November 12th, 2004

The architectural material glass has refraction. Refracted transparency cannot have an alpha channel.

Set the IOR to 1.0 and it should have a transparent alpha.

Alexander

Ras · November 15th, 2004

Hi Alexander

Thank you very much for your answer.

So let me see... I cannot use caustics then - I guess caustics are refraction dependent - right?

Also - I´ll loose the nice distortion that glass with thickness produces (like a prism) when IOR is 1, right?

What kind of glass do you recommend that I use then if I want to have alpha channel mapping available and still have realistic looking glass?

October 29th, 2004	#1 (permalink)
Ras Senior Member Join Date: Oct 2002 Location: Denmark Posts: 196 Name: Rasmus Groth	Architectural glass opacity missing alpha channel Hi again I´ve run into a problem with my Architectural glass and alpha channels. It seems that when i save my image and try to use the alpha channel to map my background into the picture the glass appears as a completely opaque object?!? I don´t know how to work aroun this problem. I have no problem when using a standard material with for example 20% opacity but Architectural glass is so much nicer... What to do? __________________ Regards Ras

November 12th, 2004	#2 (permalink)
Ras Senior Member Join Date: Oct 2002 Location: Denmark Posts: 196 Name: Rasmus Groth	Re: Architectural glass opacity missing alpha channel Helloooooo?!? [knock-knock] Is this thing on? __________________ Regards Ras

November 12th, 2004	#3 (permalink)
abicalho Veteran Member Join Date: Dec 2001 Location: San Francisco Age: 35 Posts: 643 Name: Alex Bicalho	Re: Architectural glass opacity missing alpha channel The architectural material glass has refraction. Refracted transparency cannot have an alpha channel. Set the IOR to 1.0 and it should have a transparent alpha. Alexander

November 15th, 2004	#4 (permalink)
Ras Senior Member Join Date: Oct 2002 Location: Denmark Posts: 196 Name: Rasmus Groth	Re: Architectural glass opacity missing alpha channel Hi Alexander Thank you very much for your answer. So let me see... I cannot use caustics then - I guess caustics are refraction dependent - right? Also - I´ll loose the nice distortion that glass with thickness produces (like a prism) when IOR is 1, right? What kind of glass do you recommend that I use then if I want to have alpha channel mapping available and still have realistic looking glass? __________________ Regards Ras

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