POV-Ray : Newsgroups : povray.binaries.images : Misty mountains impression : Re: Misty mountains impression Server Time
22 Jan 2022 19:51:52 EST (-0500)
  Re: Misty mountains impression  
From: Thomas de Groot
Date: 23 Sep 2021 02:49:12
Message: <614c2368@news.povray.org>
Op 22/09/2021 om 20:57 schreef Cousin Ricky:
> On 2021-09-21 2:27 AM (-4), Thomas de Groot wrote:
>>
>> Yes? However, now I would like to see a combination of both: hills (4th)
>> with haze (3rd). I am effectively missing a (bluish) distant haze in the
>> 4th generation hills, which, you certainly have observed. Similarly, in
>> France, when visiting the Vosges region, one speaks of "La ligne bleue
>> des Vosges" i.e. "the blue line (or silhouette) of the Vosges".
> 
> Yes, I have indeed noticed that.  Sky is something I've been struggling
> a long time to get right, and this certainly isn't the final form.  I
> have a lot to learn about what colors the sky.  There is a blue haze in
> the 4th generation image, but it is subtle.  I used just enough ground
> fog to reproduce the brightness gradient I see in photos, but this
> doesn't seem to translate well to extinction.  I wonder if this is
> because POV-Ray's ground fog is flat, while the Earth is not.  There is
> also turbidity to be considered.
> 
> The color of the haze also varies depending on what's in the air.  In
> the Caribbean, it is whitish when Sahara dust crosses the Atlantic.  In
> the northeastern USA, the haze is brownish, I presume due to nitrogen
> oxides.
> 
> I see media in a future implementation, but it is currently low priority.
> 
Media certainly is an option. However, before that, have you seen this 
(2005)?
 
http://news.povray.org/povray.binaries.images/thread/%3C424df1e1%241%40news.povray.org%3E/

> Attached are 1st and 4th generation scenes.  I wrote the first
> generation render rig in 2003 withing a month of downloading POV-Ray,
> and as you can see, the sky is just a plain background.  The 4th
> generation scene has the hills maxed out at 5000 meters, and I
> implemented the rig so that higher elevation caps push the hills
> proportionately further into the background.  It's been a few years
> since I wrote the code, but I estimate the hills are on the order of 20
> km away from the camera.
> 
> A 2nd generation scene is not shown, because it did not provide an
> automatic sky.
>
I like those generation comparisons. Very comprehensive indeed.

-- 
Thomas


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