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26 Dec 2024 00:44:31 EST (-0500)
  cloud texture experiments - sunset (Message 1 to 4 of 4)  
From: Abe
Subject: cloud texture experiments - sunset
Date: 17 Apr 2004 23:30:30
Message: <4081f656@news.povray.org>
Continuing with the idea of shading a 2D texture to appear 3D.

The trick seems to be to pick a point and march along a ray on the sky 
plane toward the sun, sampling the 2D cloud texture along the way. Based 
  on the samples collected, the point is assigned a degree of 
"illumination" or brightness.

I have a lot of fun with the idea, but so far my implementation is no 
where near as elegant as I think it could be. Come to think of it, 
writing it as a shader for POVman might be smoother.

What's here is a set of layered textures which have the following tasks 
(in order): sky color, sun and sun glow, base cloud color, cloud 
illumination, haze, flare.

What's not here is any attempt at implementing pronounced forward 
scattering or multiple scattering effects. There is also no 
comprehensive model which steers the different colors - they are all set 
individually through trial and error (and will probably still be off 
when I get a chance to look at them on a CRT!).

Abe


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Attachments:
Download 'sunset_progression.jpg' (71 KB) Download 'sunset.jpg' (62 KB)

Preview of image 'sunset_progression.jpg'
sunset_progression.jpg

Preview of image 'sunset.jpg'
sunset.jpg


 

From: Marc Jacquier
Subject: Re: cloud texture experiments - sunset
Date: 18 Apr 2004 02:44:25
Message: <408223c9$1@news.povray.org>

4081f656@news.povray.org...
> Continuing with the idea of shading a 2D texture to appear 3D.
/...

Splendid!
Marc


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From: Alain
Subject: Re: cloud texture experiments - sunset
Date: 18 Apr 2004 09:12:00
Message: <40827ea0$1@news.povray.org>
Abe nous apporta ses lumieres ainsi en ce 2004/04/17 23:29... :

> Continuing with the idea of shading a 2D texture to appear 3D.
>
> The trick seems to be to pick a point and march along a ray on the sky 
> plane toward the sun, sampling the 2D cloud texture along the way. 
> Based  on the samples collected, the point is assigned a degree of 
> "illumination" or brightness.
>
> I have a lot of fun with the idea, but so far my implementation is no 
> where near as elegant as I think it could be. Come to think of it, 
> writing it as a shader for POVman might be smoother.
>
> What's here is a set of layered textures which have the following 
> tasks (in order): sky color, sun and sun glow, base cloud color, cloud 
> illumination, haze, flare.
>
> What's not here is any attempt at implementing pronounced forward 
> scattering or multiple scattering effects. There is also no 
> comprehensive model which steers the different colors - they are all 
> set individually through trial and error (and will probably still be 
> off when I get a chance to look at them on a CRT!).
>
> Abe
>
> ------------------------------------------------------------------------
>
>
> ------------------------------------------------------------------------
>
The big one look like an actual photo, I've seen real clouds loking the 
same. Very realistic. I'm using a CTR.

Alain


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From: Felbrigg
Subject: Re: cloud texture experiments - sunset
Date: 19 Apr 2004 04:38:39
Message: <4083900f$1@news.povray.org>
V.v.v.v.v.v.v.v.v.v.v. nice whats the render time like on these?



"Abe" <bul### [at] taconicnet> wrote in message
news:4081f656@news.povray.org...
> Continuing with the idea of shading a 2D texture to appear 3D.
>
> The trick seems to be to pick a point and march along a ray on the sky
> plane toward the sun, sampling the 2D cloud texture along the way. Based
>   on the samples collected, the point is assigned a degree of
> "illumination" or brightness.
>
> I have a lot of fun with the idea, but so far my implementation is no
> where near as elegant as I think it could be. Come to think of it,
> writing it as a shader for POVman might be smoother.
>
> What's here is a set of layered textures which have the following tasks
> (in order): sky color, sun and sun glow, base cloud color, cloud
> illumination, haze, flare.
>
> What's not here is any attempt at implementing pronounced forward
> scattering or multiple scattering effects. There is also no
> comprehensive model which steers the different colors - they are all set
> individually through trial and error (and will probably still be off
> when I get a chance to look at them on a CRT!).
>
> Abe
>


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