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From: St 
Subject: Heat haze...
Date: 18 May 2004 14:32:23
Message: <40aa56b7@news.povray.org>
Can this be done with Pov? I would imagine that focal_blur could/would
be used, but how would you produce that undulating, blurred, wavy
effect behind your scene?

 Any ideas?

 ~Steve~


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From: Gilles Tran
Subject: Re: Heat haze...
Date: 18 May 2004 15:14:30
Message: <40aa6096@news.povray.org>

news:40aa56b7@news.povray.org...
> Can this be done with Pov? I would imagine that focal_blur could/would
> be used, but how would you produce that undulating, blurred, wavy
> effect behind your scene?

Untried, but in some circumstances I guess that a smart normal in the
camera{} could do the trick.

G.

-- 
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters


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From: ingo
Subject: Re: Heat haze...
Date: 18 May 2004 15:34:49
Message: <Xns94EDDB865CB5Dseed7@news.povray.org>
in news:40aa6096@news.povray.org Gilles Tran wrote:

> Untried, but in some circumstances I guess that a smart normal in the
> camera{} could do the trick.
> 

Or a transparant non reflective plane with a normal and ior, about halfway 
the depth of the scene. A gradient could be used to control the density 
from the normal towards the sky.


Ingo


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From: Rune
Subject: Re: Heat haze...
Date: 18 May 2004 17:48:51
Message: <40aa84c3$1@news.povray.org>
Gilles Tran wrote:
> Untried, but in some circumstances I guess that a
> smart normal in the camera{} could do the trick.

There probably are cases where it suffices, but in general this solution
is not suitable, since it is not dependent on distance. This creates two
related problems:

- The turbulence is equally strong for close and distant parts of the
scene. (I.e. it does not add up.)
- The turbulence pattern does not follow the perspective - that is, it
doesn't become smaller with distance.

In effect, using a normal in the camera will simulate heat that is
located right where the camera is and not in the rest of the scene.

For a suggestion that IMHO will often create more useful results, see
Ingo's reply.

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com **updated Apr 27**
POV-Ray Ring: http://webring.povray.co.uk


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From: Shay
Subject: Re: Heat haze...
Date: 18 May 2004 17:58:42
Message: <40aa8712$1@news.povray.org>
"St." <dot### [at] dotcom> wrote in message news:40aa56b7@news.povray.org...

The details would have to be worked out, but the basics of my idea would
be to first make a distance-information render where every surface is
colored according to it's distance from the camera, then to use this
information in combination with a heat-wave looking pigment function to
blur surrounding pixels of a full-color render in a heat-wave style
pattern. Something like: blur=distance*heat-wavefunc.

 -Shay


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From: Warp
Subject: Re: Heat haze...
Date: 18 May 2004 18:32:53
Message: <40aa8f15@news.povray.org>
Shay <rrr.rrr.r> wrote:
> Something like: blur=distance*heat-wavefunc.

  But fluctuations in air temperature doesn't cause blur, it causes
variations in the IOR of the air which is completely different thing.

-- 
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: Alain
Subject: Re: Heat haze...
Date: 18 May 2004 19:11:10
Message: <40aa980e$1@news.povray.org>
St. nous apporta ses lumieres ainsi en ce 2004/05/18 14:32... :

>Can this be done with Pov? I would imagine that focal_blur could/would
>be used, but how would you produce that undulating, blurred, wavy
>effect behind your scene?
>
> Any ideas?
>
> ~Steve~
>
>
>
>  
>
I tought of a trick:
Use a serie of invisible refractive boxes with small normal variations 
and low iors (1.001 to 1.1) set at a scale that increase with the 
distance from the camera. Increase max_trace_level by double the number 
of boxes. That way, distent objects will get more distortion than close 
ones. It's obvious that it will also increase render time. The boxes 
have to be large enough to cover all the visible area and hollow if you 
have any media like some fog.

I never tested it.

Alain


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From: Sally
Subject: Re: Heat haze...
Date: 18 May 2004 20:19:38
Message: <40aaa81a$1@news.povray.org>
On a related note, how do you get distance information from a regular
povray scene?


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From: Gilles Tran
Subject: Re: Heat haze...
Date: 18 May 2004 21:21:37
Message: <40aab6a1@news.povray.org>

news:40aa84c3$1@news.povray.org...

> There probably are cases where it suffices, but in general this solution
> is not suitable, since it is not dependent on distance. This creates two
> related problems:

I know, I know, but it's cheap (to create) and fast (to render), and cheap
and fast solutions should always be tried before more expensive and slower
ones... Hey, even in big budget movies they use sock puppets instead of CGI
sometimes :)

G.


-- 
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters


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From: Rune
Subject: Re: Heat haze...
Date: 19 May 2004 02:49:29
Message: <40ab0379@news.povray.org>
Gilles Tran wrote:
>
> Rune wrote:
>> There probably are cases where it suffices, but
>> in general this solution is not suitable, since
>> it is not dependent on distance.
>
> I know, I know, but it's cheap (to create) and
> fast (to render), and cheap and fast solutions
> should always be tried before more expensive and
> slower ones...

True. :)

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com **updated Apr 27**
POV-Ray Ring: http://webring.povray.co.uk


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