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From: John M  Dlugosz
Subject: Lighting for Bright Sunlight
Date: 29 Feb 2004 22:20:21
Message: <4042abf5@news.povray.org>
It's been a while since I've used POV, but I'm confortable 
enough so I don't need hand-holding answers and I can look 
things up in the docs when pointed in the right direction.

I'm rendering a Gazebo, and I want it to be in bright Dallas 
sunshine.  So, one light source in the right spot, and yow, 
the contrast is too high.  The shadows are too dark.  Yea, 
it really does look like that, but the eye adjusts as you 
look around.  I tried turning up the ambient light setting 
but it doesn't look good.  I threw in a fill-light with 
"shadowless" and it does help.

But any more expert suggestions?  Real light is the bright 
sun plus a general glow from the whole sky.  A huge area 
light would be inefficient.  The "ambient" light is much 
less under the roof than outside, but there's no direct way 
to say that that I recall.

--John


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From: Rafal 'Raf256' Maj
Subject: Re: Lighting for Bright Sunlight
Date: 29 Feb 2004 22:29:13
Message: <Xns949F2D9479CBraf256com@203.29.75.35>
wtb### [at] sneakemailcom news:4042abf5@news.povray.org

> I'm rendering a Gazebo, 

What is an Gazebo?

> and I want it to be in bright Dallas 
> sunshine.  So, one light source in the right spot, and yow, 
> the contrast is too high.  The shadows are too dark.  Yea, 
> it really does look like that, but the eye adjusts as you
> look around.  I tried turning up the ambient light setting 
> but it doesn't look good.  I threw in a fill-light with 
> "shadowless" and it does help.

You should use radiosity,
for a quick test just add at begin of .pov scene:

  global_settings{radiosity{}}

and probably You also would like to add:

 default{finish{ambient 0}}

then all (most) object would be lighten not only by light_sources, by also 
by sorounding objects that reflect (diffuse) light.

Light will be "produced" by ambient objects (including sky_sphere) and 
objects with i.e. finish{ambient 1}

You also my try HDRI instead sky_sphere (You need ML POV patch instead of 
Pov 3.6 for it).

In addition You might want to use area_light.
For radiosity You might want to use higher quality settings in final 
render.


-- 
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics


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From: Tek
Subject: Re: Lighting for Bright Sunlight
Date: 29 Feb 2004 22:51:29
Message: <4042b341@news.povray.org>
I recommend Jaime Vives Piqueres' lighting system, which supports real world
lighting values and colours:
http://www.ignorancia.org/t_lightsys.php

The bit I use the most is his Kelvin() macro, where you pass in a colour
temperature and it gives you rgb values. The sun has a colour of around
Kelvin(5500).

If you want to look at my best sunny lighting setup, you can download the source
for my "grassy" image:
http://www.evilsuperbrain.com/gallery/showimage.php?name=finished/grassy
It has a "dome" of 8 blue lights with one strong directional one.

Cheers
-- 
Tek
www.evilsuperbrain.com

"John M. Dlugosz" <wtb### [at] sneakemailcom> wrote in message
news:4042abf5@news.povray.org...
> It's been a while since I've used POV, but I'm confortable
> enough so I don't need hand-holding answers and I can look
> things up in the docs when pointed in the right direction.
>
> I'm rendering a Gazebo, and I want it to be in bright Dallas
> sunshine.  So, one light source in the right spot, and yow,
> the contrast is too high.  The shadows are too dark.  Yea,
> it really does look like that, but the eye adjusts as you
> look around.  I tried turning up the ambient light setting
> but it doesn't look good.  I threw in a fill-light with
> "shadowless" and it does help.
>
> But any more expert suggestions?  Real light is the bright
> sun plus a general glow from the whole sky.  A huge area
> light would be inefficient.  The "ambient" light is much
> less under the roof than outside, but there's no direct way
> to say that that I recall.
>
> --John


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From: Richard Dybiec
Subject: Re: Lighting for Bright Sunlight
Date: 1 Mar 2004 13:27:56
Message: <404380ac@news.povray.org>
John M. Dlugosz wrote:
> It's been a while since I've used POV, but I'm confortable enough so I 
> don't need hand-holding answers and I can look things up in the docs 
> when pointed in the right direction.
> 
> I'm rendering a Gazebo, and I want it to be in bright Dallas sunshine.  
> So, one light source in the right spot, and yow, the contrast is too 
> high.  The shadows are too dark.  Yea, it really does look like that, 
> but the eye adjusts as you look around.  I tried turning up the ambient 
> light setting but it doesn't look good.  I threw in a fill-light with 
> "shadowless" and it does help.
> 
> But any more expert suggestions?  Real light is the bright sun plus a 
> general glow from the whole sky.  A huge area light would be 
> inefficient.  The "ambient" light is much less under the roof than 
> outside, but there's no direct way to say that that I recall.
> 
> --John
I generally create the simplest of light arrays, two 'suns', one that 
will cast shadows and one thats shadowless.  By adjusting the light 
color of each, you can get the degree of contrast you desire.  Adding 
two or three 'fill' lights in addition will give you even better 
control.  I try to stay away from ambient light altogether, except for 
testing geometry.

rd


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From: John M  Dlugosz
Subject: Re: Lighting for Bright Sunlight
Date: 1 Mar 2004 19:49:25
Message: <4043da15$1@news.povray.org>
Rafal 'Raf256' Maj wrote:
> What is an Gazebo?

"A freestanding, roofed, usually open-sided structure 
providing a shady resting place."
> You should use radiosity,
> Light will be "produced" by ambient objects (including sky_sphere) and 
> objects with i.e. finish{ambient 1}

I'll have to read up on that again.  When it was first 
available, it was picky to use and =way= too slow!


> You also my try HDRI instead sky_sphere (You need ML POV patch instead of 
> Pov 3.6 for it).

What is HDRI?

> In addition You might want to use area_light.

As I recall, the area light affects the apparence of the 
shadow but =not= the illumination shading.

Thanks,
--John


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From: John M  Dlugosz
Subject: Re: Lighting for Bright Sunlight
Date: 1 Mar 2004 19:53:29
Message: <4043db09$1@news.povray.org>
Tek wrote:

> http://www.ignorancia.org/t_lightsys.php
> http://www.evilsuperbrain.com/gallery/showimage.php?name=finished/grassy

Many thanks for both tips.

Beautiful image, BTW.

--John


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From: John M  Dlugosz
Subject: Re: Lighting for Bright Sunlight
Date: 1 Mar 2004 19:56:36
Message: <4043dbc4$1@news.povray.org>
Richard Dybiec wrote:
> I generally create the simplest of light arrays, two 'suns', one that 
> will cast shadows and one thats shadowless.  By adjusting the light 
> color of each, you can get the degree of contrast you desire. 

Both in the same place?  I see; that gives you lighter shadows.


> Adding 
> two or three 'fill' lights in addition will give you even better 
> control.  I try to stay away from ambient light altogether, except for 
> testing geometry.

I read a pretty good book about digital lighting, and 
basically you light it the way you would in photography. 
But dozens of lights slows things down and are hard to 
position just right.


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From: Christopher James Huff
Subject: Re: Lighting for Bright Sunlight
Date: 3 Mar 2004 22:49:16
Message: <cjameshuff-B76C0F.22501703032004@news.povray.org>
In article <4043dbc4$1@news.povray.org>,
 "John M. Dlugosz" <wtb### [at] sneakemailcom> wrote:

> Both in the same place?  I see; that gives you lighter shadows.

Hmm. I always set the default texture to have an ambient of 0 and 
diffuse of 1. I then usually put a dim white shadowless fill light at 
the camera location...edges still get shaded, so it doesn't flatten the 
scene out like ambient light. Nice for test renders: it doesn't hide the 
geometry of an object, and illuminates everything that's visible. 
Depending on the scene, I'll disable it or dim it further, and use 
radiosity for the final render.

In this case, you are using the second light to simulate scattered 
sky-light. Radiosity will do an actual optical simulation of this, but a 
shadowless blueish light in the general area of the greatest amount of 
visible sky can give similar results. A slightly yellowish light and one 
or more blue-tinted lights at separate positions can give the scene a 
lot more depth, but a blue sky and radiosity will do a better job.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/


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From: Christopher James Huff
Subject: Re: Lighting for Bright Sunlight
Date: 3 Mar 2004 22:55:53
Message: <cjameshuff-67D978.22565503032004@news.povray.org>
In article <4043da15$1@news.povray.org>,
 "John M. Dlugosz" <wtb### [at] sneakemailcom> wrote:

> Rafal 'Raf256' Maj wrote:
> > What is an Gazebo?
> 
> "A freestanding, roofed, usually open-sided structure 
> providing a shady resting place."

An ideal radiosity scene.


> > You should use radiosity,
> > Light will be "produced" by ambient objects (including sky_sphere) and 
> > objects with i.e. finish{ambient 1}
> 
> I'll have to read up on that again.  When it was first 
> available, it was picky to use and =way= too slow!

Try it again. Don't forget to look at the rad_def.inc include file (part 
of the standard distribution). It's been greatly improved in quality and 
speed since the earliest versions.


> > You also my try HDRI instead sky_sphere (You need ML POV patch instead of 
> > Pov 3.6 for it).
> 
> What is HDRI?

High Dynamic Range Image. An image format that can store values outside 
of a 0-100% range. It doesn't necessarily give more realistic results in 
POV because color values used internally are unclipped anyway, but it 
allows you to use precalculated or real-world samples for distant 
surroundings.


> > In addition You might want to use area_light.
> 
> As I recall, the area light affects the apparence of the 
> shadow but =not= the illumination shading.

Correct. However, the soft shadow can sometimes give an appearance 
similar to actual radiosity.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/


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From: Xplo Eristotle
Subject: Re: Lighting for Bright Sunlight
Date: 21 Mar 2004 09:11:49
Message: <405da2a5@news.povray.org>
John M. Dlugosz wrote:
> It's been a while since I've used POV, but I'm confortable enough so I 
> don't need hand-holding answers and I can look things up in the docs 
> when pointed in the right direction.
> 
> I'm rendering a Gazebo, and I want it to be in bright Dallas sunshine.  
> So, one light source in the right spot, and yow, the contrast is too 
> high.  The shadows are too dark.  Yea, it really does look like that, 
> but the eye adjusts as you look around.

One thing you might want to keep in mind is that a monitor will probably 
have MUCH too small a contrast range to display this scene accurately.. 
so, rather than trying to make it look physically real, you should 
settle for making it look "good". You might consider using photographs 
of similar real-world environments for reference.

-Xplo


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