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25 Nov 2024 07:42:46 EST (-0500)
  A "sun" light... (Message 1 to 4 of 4)  
From: Gyscos
Subject: A "sun" light...
Date: 29 Apr 2006 08:10:00
Message: <web.445357109cc843651ba56a630@news.povray.org>
Hello everyone !!!
Now i'm trying to make a sun-like light_source...
When i say sun-like I mean :
-> Parralel light, or very far light source, so that it seems parralel
-> No 100% black shadow : the objects around me reflect light a little bit
and light my shadow : in real life, during the day, there are very few 100%
black shadow...
-> When a non-sun-like light source make a shafow, THIS shadow is black,
only sun-like light source can have smooth shadow...

I considered using area_light, but the sun isn't really an area  from the
Earth, and anyway that still leave hard shadows...

Does someone have an idea ?


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From: Tim Nikias
Subject: Re: A "sun" light...
Date: 29 Apr 2006 08:16:31
Message: <4453591f@news.povray.org>
> -> Parralel light, or very far light source, so that it seems parralel

There's the parallel keyword for lightsources, use it with point_at in the
lightsource and your good to go.

> -> No 100% black shadow : the objects around me reflect light a little bit
> and light my shadow : in real life, during the day, there are very few
100%
> black shadow...

You might want to look at radiosity, or using shadowless lights to crudely
model the way light bounces off of objects and illuminates the shadows.
Three-point-lighting is another term you might want to google.

> -> When a non-sun-like light source make a shafow, THIS shadow is black,
> only sun-like light source can have smooth shadow...

Arealights takes care of sharp and smooth shadows, depend on how big you set
them.


Hope that gets you started.

Regards,
Tim

-- 
aka "Tim Nikias"
Homepage: <http://www.nolights.de>


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From: Gyscos
Subject: Re: A "sun" light...
Date: 29 Apr 2006 09:35:01
Message: <web.44536b477a93ead91ba56a630@news.povray.org>
Woow radiosity  is really cool !
I think that's what I've been searching. Thank you !


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From: Warp
Subject: Re: A "sun" light...
Date: 29 Apr 2006 10:07:40
Message: <4453732c@news.povray.org>
Gyscos <gys### [at] gmailcom> wrote:
> -> When a non-sun-like light source make a shafow, THIS shadow is black,
> only sun-like light source can have smooth shadow...

  On what do you base this assumption? It doesn't work like that in real
life.

> I considered using area_light, but the sun isn't really an area  from the
> Earth, and anyway that still leave hard shadows...

  Actually the Sun is not a point light. If you eg. photograph the sun
(with the camera set up so that you can see the disc of the sun, eg. by
using a strong filter) you see that it is a disc with a visible size.
Thus the sun is an area light.
  Moreover, the atmosphere scatters the light, and this effect is
especially strong when the sky is a bit cloudy. When the sun shines
from behind a cloud, all shadows are really smooth.

-- 
                                                          - Warp


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