POV-Ray : Newsgroups : povray.animations : alpha channel in animations Server Time
8 Jul 2024 14:32:20 EDT (-0400)
  alpha channel in animations (Message 14 to 23 of 23)  
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From: Remco de Korte
Subject: Re: alpha channel in animations
Date: 27 Feb 2003 12:57:17
Message: <3E5E50BD.E3E18F4B@onwijs.com>
Tom Galvin wrote:
> 
> Remco de Korte <rem### [at] onwijscom> wrote in
> news:3E5D3E1B.6CB45246@onwijs.com:
> > I'm also looking for some cheap (or free) editing program. I don't
> > really expect that to do the kind of thing I need (= blend live action
> > over a rendered background - probably...)
> >
> > Remco
> >
> 
> You may want to look at http://filmgimp.sourceforge.net/
> 
> It is open source and used professionally by the hollywood studios.  The
> Windows version is due to be released any day now.

Thank you.

Remco


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From: Scott Moore
Subject: Re: alpha channel in animations
Date: 28 Feb 2003 09:34:45
Message: <ujsu5vcp21c6k1fnhabuesorgoa6o6bni1@4ax.com>
On Wed, 26 Feb 2003 12:18:49 +0100, "Fabien Mosen"
<fab### [at] skynetbe> wrote:

>Do you know of any video format that preserves the alpha
>channel of the rendered frames ?
Hi Fabien,

I too was trying this recently - wasn't able to get it to work with
.avi files but could with Quicktime .mov files (although you'll need
to purchase Quicktime Pro ($30) to create .mov files)

Cheers,

Scott


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From: Fabien Mosen
Subject: Re: alpha channel in animations
Date: 28 Feb 2003 15:03:12
Message: <3e5fc080@news.povray.org>
Warp wrote:
> Fabien Mosen <fab### [at] skynetbe> wrote:
> 
>>(BTW, it would greatly help if POV-Ray was able to output the alpha
>>channel as separate grayscale frames, as it seems that it's what
>>commercial renderers do.)
> 
> 
>   That's odd and sounds cumbersome.

So much ?  In general, I would like to see POV-Ray being able to output
various information in the form of deep-grayscale images aside the
main rendering : alpha, normals, depth...  It would allow easy
postprocessing with existing tools (even for stills).  BTW, most
commercial renderers do that.

> (Or is some kind of odd principle the
> have that they don't support png, period?)

I don't think so.  It might be simply that they are made to get
video as input, and not series of still frames.  Again, commercial
renderers outputs animations as animations, not as series of stills.

Fabien.


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From: Andrew Coppin
Subject: Re: alpha channel in animations
Date: 2 Mar 2003 14:49:33
Message: <3e62604d@news.povray.org>
Animated GIF anyone?

(Excuse me while I kill myself laughing)
Andrew.


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From: Warp
Subject: Re: alpha channel in animations
Date: 2 Mar 2003 19:27:23
Message: <3e62a16b@news.povray.org>
Andrew Coppin <orp### [at] btinternetcom> wrote:
> Animated GIF anyone?

  I didn't know GIFs support an alpha channel.

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -


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From: Andrew Coppin
Subject: Re: alpha channel in animations
Date: 3 Mar 2003 15:01:52
Message: <3e63b4b0@news.povray.org>
You've never heard of a transparent GIF??? OK, it only supports 1-bit alpha
(i.e., transparency = 100% or 0%, not in between). But you can animate it.

Wasn't really a "serious" suggestion ;-)
Andrew.


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From: Phil Clute
Subject: Re: alpha channel in animations
Date: 4 Mar 2003 04:30:30
Message: <3e647236@news.povray.org>
> Or any other procedure
> that will allow us to manage the transparency information
> with the compositing software ?

Probably not the answer you're looking for but you
could render it with a blue or green screen. Compositing
software should have this available. Zei-Stein is
free and will do it:
http://www.thugsatbay.com/


-- 
Phil


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From: Warp
Subject: Re: alpha channel in animations
Date: 4 Mar 2003 12:10:19
Message: <3e64ddfa@news.povray.org>
Andrew Coppin <orp### [at] btinternetcom> wrote:
> You've never heard of a transparent GIF??? OK, it only supports 1-bit alpha
> (i.e., transparency = 100% or 0%, not in between). But you can animate it.

  GIF does not support an alpha channel.

  You can define that one of the colors is (completely) transparent, but
that's not an alpha channel. An alpha channel means that every color,
besides having red, green and blue values, also has a fourth component,
the transparency (ie. alpha) value. That is, colors have four components
instead of three.

> Wasn't really a "serious" suggestion ;-)

  I know. I just wanted to clear any misconceptions that might arise.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -


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From: Remco de Korte
Subject: Re: alpha channel in animations
Date: 4 Mar 2003 12:29:11
Message: <3E64E196.E874498D@onwijs.com>
Andrew Coppin wrote:
> 
> You've never heard of a transparent GIF??? OK, it only supports 1-bit alpha
> (i.e., transparency = 100% or 0%, not in between). But you can animate it.
> 
> Wasn't really a "serious" suggestion ;-)
> Andrew.

The New GIF format has an alpha channel but it is still in beta.

Remco


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From: Fabien Mosen
Subject: Re: alpha channel in animations
Date: 5 Mar 2003 13:04:56
Message: <3e663c48@news.povray.org>
Phil Clute wrote:

> Probably not the answer you're looking for but you
> could render it with a blue or green screen. 

We tried that, and it doesn't work well with transparent
areas...

Currently, we render with a black background and use
some additive compositing.

Fabien.


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