POV-Ray : Newsgroups : povray.general : setting background transparency Server Time
26 Dec 2024 02:18:16 EST (-0500)
  setting background transparency (Message 1 to 4 of 4)  
From: Alex McMurray
Subject: setting background transparency
Date: 5 Jul 2007 17:25:25
Message: <468d61c5@news.povray.org>
Hello all,

I'm trying to come to grips with setting background transparency into a 
mapped image.

eg, I have a photograph of a person, in photoshop I have erased the 
background and made it transparent leaving only the image of the person,
In Povray, I have mapped the image onto a surface, in this case a cube with 
nearly zero depth, I need the cube made transparent, but leave the image of 
the person solid.
I have followed the help manual but maybe I am not understanding it 
properly, as all the image is made transparent.
Any further help will be gladely accepted before I lose any more hair.

Alex.


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From: Marc
Subject: Re: setting background transparency
Date: 5 Jul 2007 17:48:30
Message: <468d672e$1@news.povray.org>

468d61c5@news.povray.org...
> Hello all,
>
> I'm trying to come to grips with setting background transparency into a 
> mapped image.
>
You must save your image in a format which includes alpha channel 
(transparency information) as PNG or TGA.

Marc


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From: Tim Attwood
Subject: Re: setting background transparency
Date: 5 Jul 2007 18:30:28
Message: <468d7104$1@news.povray.org>
> Hello all,
>
> I'm trying to come to grips with setting background transparency into a 
> mapped image.
>
> eg, I have a photograph of a person, in photoshop I have erased the 
> background and made it transparent leaving only the image of the person,
> In Povray, I have mapped the image onto a surface, in this case a cube 
> with nearly zero depth, I need the cube made transparent, but leave the 
> image of the person solid.
> I have followed the help manual but maybe I am not understanding it 
> properly, as all the image is made transparent.
> Any further help will be gladely accepted before I lose any more hair.
>
> Alex.

You need to use a PNG, or TGA format image for the image map.
These formats support an Alpha channel. (Alpha = transparency)

A cube will have a back face, which you don't want, the easiest way to
deal with getting just one face is to use a plane instead, then you can
use "once" in your image map.

You don't need to change the output format, or to output transparency
in your image for what you are describing, but if you wanted to output
a partially transparent image, you could use +ua in the command line,
and make sure you are using PNG with +fn, or TGA with +ft in the
command line.


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From: Alex McMurray
Subject: Re: setting background transparency
Date: 7 Jul 2007 17:30:40
Message: <46900600@news.povray.org>
Thank Tim & Marc.

That worked, I was using jpeg format, converted to png.

Thanks once again.

Alex.


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