Here is a picture that uses the nighttime earth image featured a couple of
days ago on the Astronomy Picture of the Day web page. The image can be
downloaded now at:

http://antwrp.gsfc.nasa.gov/apod/image/0011/earthlights_dmsp_big.jpg



Below is the simple code I used to generate it. Pretty basic, but it makes a
nice picture, and a good background screen.

// Persistence of Vision Ray Tracer Scene Description File
#version 3.1

#include "colors.inc"

global_settings {
  assumed_gamma 1.0
}

camera {
  location  <0.0, 3.5, -3.0>
  direction 1.5*z
  right     4/3*x
  look_at   <0.0, 1.0,  0.0>
}

background { color Black }

light_source {
  0*x
  color White
  translate <-8, 3, 30>
}

sphere {
  <0, 0, 0>
  0.5
  texture {
    finish {
      ambient 0.7
      diffuse 0.9
    }
    pigment {
      image_map {
        png "earthlights_dmsp_big.png"
        map_type 1
        interpolate 2
      }
    }
  }
  rotate <0,-140,0>
  scale 2
  translate <0,1,0>
}

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Attachments:
Download 'earth.jpg' (17 KB)

Preview of image 'earth.jpg'

Jon Berndt wrote:
> 
> Here is a picture that uses the nighttime earth image featured a couple of
> days ago on the Astronomy Picture of the Day web page. The image can be
> downloaded now at:
> 
> http://antwrp.gsfc.nasa.gov/apod/image/0011/earthlights_dmsp_big.jpg 

	Thank you good sir, a thousand thank yous. May Allah bless you. That is
exactly the image I have been looking for, for a year now. 

	And since you post the code. I plan a daylight sphere and a night
sphere trivially displaced so that half is dark and half is light. And
that being animation material. 

> Below is the simple code I used to generate it. Pretty basic, but it makes a
> nice picture, and a good background screen.
> 
> // Persistence of Vision Ray Tracer Scene Description File
> #version 3.1
> 
> #include "colors.inc"
> 
> global_settings {
>   assumed_gamma 1.0
> }
> 
> camera {
>   location  <0.0, 3.5, -3.0>
>   direction 1.5*z
>   right     4/3*x
>   look_at   <0.0, 1.0,  0.0>
> }
> 
> background { color Black }
> 
> light_source {
>   0*x
>   color White
>   translate <-8, 3, 30>
> }
> 
> sphere {
>   <0, 0, 0>
>   0.5
>   texture {
>     finish {
>       ambient 0.7
>       diffuse 0.9
>     }
>     pigment {
>       image_map {
>         png "earthlights_dmsp_big.png"
>         map_type 1
>         interpolate 2
>       }
>     }
>   }
>   rotate <0,-140,0>
>   scale 2
>   translate <0,1,0>
> }
> 
>  [Image]

-- 
Kicking the crap out of Canadian Nationals is half the fun
in life. Who would imagine an ice hockey team in Tampa. I 
do love the Hansen Brothers even though they are Canadians. 
	-- The Iron Webmaster, 174

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All I can say is WOW
& That is my new wallpaper

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Matt Giwer wrote:
> 
>         Thank you good sir, a thousand thank yous. May Allah bless you. That is
> exactly the image I have been looking for, for a year now.

You are most welcome. It seemed like the kind of picture somebody surely must be
able to use!

>         And since you post the code. I plan a daylight sphere and a night
> sphere trivially displaced so that half is dark and half is light. And
> that being animation material.

I considered this, too, and, given the right daytime earth image, I might
eventually try it, as well. Post your results when you get something. I'd like
to see it.

I was trying to think of how it could be most realistically done. Would a
layered texture work? I don't know.

There does exist a daylight version of the nighttime pic I posted the URL for.
If I can find it I'll post the URL for that, as well.

Jon

-- 
--------------------------------------------------------------

Jon S. Berndt
League City, Texas
jsb### [at] hal-pcorg

--------------------------------------------------------------

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I was thinking about this too, and I think that using either a gradient texture or a
slope-dependent texture map to blend between the light and the dark image maps would
probably work fairly well.

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I'd like to try it so that you can model it closer to reality: that is,
letting your light source "sun" illuminate the globe so that on the night
side you see the lights, but on the day side you see the surface details and
coloration. I think this might be done by using a modified version of the
nighttime earth bitmap, making everything but the lights transparent. Then,
layer that with the earth photo bitmap (with the nighttime earth bitmap on
the "outside"). Set up the finish properties so that on the lit (day) side
the colored bitmap is overwhelmingly visible, but on the unlit side (night)
the nighttime city lights are overwhelmingly visible.

That may not be quite right, but I can't help thinking there must be a way
to do it.

Look here:

http://www.fourmilab.ch/cgi-bin/uncgi/Earth/action?opt=-p

http://livingearth.com/LE/LivEarthImg.html

I know that picture is online somewhere...

"Kevin Wampler" <wam### [at] uarizonaedu> wrote in message
news:3A269050.114FC44D@u.arizona.edu...
> I was thinking about this too, and I think that using either a gradient
texture or a
> slope-dependent texture map to blend between the light and the dark image
maps would
> probably work fairly well.
>

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Does look neat.  I missed it before because of the leading text (inline image after
it).
I did a rotating Earth with night time map from one of my satellite images CDs a while
ago.  Never uploaded it
though.

Bob

"Pabs" <pab### [at] hotmailcom> wrote in message news:3A25F050.67A00570@hotmail.com...
> All I can say is WOW
> & That is my new wallpaper

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"Jon S. Berndt" wrote:
> 
> Matt Giwer wrote:
> >
> >         Thank you good sir, a thousand thank yous. May Allah bless you. That is
> > exactly the image I have been looking for, for a year now.
> 
> You are most welcome. It seemed like the kind of picture somebody surely must be
> able to use!
> 
> >         And since you post the code. I plan a daylight sphere and a night
> > sphere trivially displaced so that half is dark and half is light. And
> > that being animation material.
> 
> I considered this, too, and, given the right daytime earth image, I might
> eventually try it, as well. Post your results when you get something. I'd like
> to see it.
> 
> I was trying to think of how it could be most realistically done. Would a
> layered texture work? I don't know.

	When I get to it, just a plain image map. Daylight on one, night on the
other. If I just shift them 0.00001 or so along an imaginary line
connecting noon with midnight and one is mathematically "above" the
other. 

> There does exist a daylight version of the nighttime pic I posted the URL for.
> If I can find it I'll post the URL for that, as well.

	I'd love to have the original of that one posted as an image on a
related website. 

-- 
It's not as though Rocker had to say No. 7 train
to know he was talking about New York City.
	-- The Iron Webmaster, 22

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> > There does exist a daylight version of the nighttime pic I posted the
URL for.
> > If I can find it I'll post the URL for that, as well.
>
> I'd love to have the original of that one posted as an image on a
> related website.

I now have one in my clutches. But, it's a couple MB in size. Probably too
big to post here. I need a volunteer to take it and put it on an FTP server.

Jon

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Attachments:
Download 'earth.jpg' (19 KB)

Preview of image 'earth.jpg'

> I now have one in my clutches. But, it's a couple MB in size. Probably too
> big to post here. I need a volunteer to take it and put it on an FTP
server.

I was wrong. I compressed it with low loss in .jpg format. I now have:

1) Earth_day.jpg   ~900Kb
2) Earth_night.jpg   ~600Kb

Should I post them separately, here, or what?

Jon

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