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28 Apr 2024 19:36:58 EDT (-0400)
  white noise pattern (Message 1 to 4 of 4)  
From: Mr
Subject: white noise pattern
Date: 8 Jan 2014 06:10:01
Message: <web.52cd3105f4dd1c4fed29e82f0@news.povray.org>
Hi,
I am searching for the povray pattern that is most suited to creating visual
black and white noise similar to what old television screens could display
without a signal. what are your advices?


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From: Jaime Vives Piqueres
Subject: Re: white noise pattern
Date: 8 Jan 2014 09:15:28
Message: <52cd5d80$1@news.povray.org>

> Hi,
> I am searching for the povray pattern that is most suited to creating visual
> black and white noise similar to what old television screens could display
> without a signal. what are your advices?
>

   The pattern doesn't matter: just use a B&W color map and turbulence 
with a high omega (>=2 will do).

--
jaime


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From: Alain
Subject: Re: white noise pattern
Date: 8 Jan 2014 18:54:45
Message: <52cde545@news.povray.org>

> Hi,
> I am searching for the povray pattern that is most suited to creating visual
> black and white noise similar to what old television screens could display
> without a signal. what are your advices?
>
>

The granite, agate or bumps patterns, properly scalled should gives good 
results. For the agate pattern, you'll need to provide a black to white 
color_map.
As those noise seems to tend to have few grays, I'd suggest a color_map 
similat to this:
color_map{[0.4 rgb 0][0.6 rgb 1]}

Change the transition range up or down to get darker or brighter patterns.
Broaden the transition range to reduce contrast, tighten it to increase it.



Alain


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From: Mr
Subject: Re: white noise pattern
Date: 8 Jan 2014 21:25:00
Message: <web.52ce0800bbe5940119dc916f0@news.povray.org>
Alain <kua### [at] videotronca> wrote:

> > Hi,
> > I am searching for the povray pattern that is most suited to creating visual
> > black and white noise similar to what old television screens could display
> > without a signal. what are your advices?
> >
> >
>
> The granite, agate or bumps patterns, properly scalled should gives good
> results. For the agate pattern, you'll need to provide a black to white
> color_map.
> As those noise seems to tend to have few grays, I'd suggest a color_map
> similat to this:
> color_map{[0.4 rgb 0][0.6 rgb 1]}
>
> Change the transition range up or down to get darker or brighter patterns.
> Broaden the transition range to reduce contrast, tighten it to increase it.
>
>
>
> Alain

Indeed, It works pretty well, I used a cell pattern to avoid getting curves in
case of big scaling


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