I enjoyed Jon Berndt's recent posting of the mosic of the earth at night
wrapped around a sphere, so I went off to see what else is new NASA and
GSFC. I stumbled across this image and, when I took a look a the 3Kx3K TIFF
version, I realized it might benefit a number of people who have been trying
to do accurate earth renderings. In particular, the atmospheric effects at
the edges of the earth are rather nicely done. This image is, as the
accompanying text on the Web site
http://rsd.gsfc.nasa.gov/rsd/bluemarble/index.html explains, a compilation
of satellite imagery and data. The large TIFF version is about 13Mb, but the
details are astounding.

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Dave Cook wrote:
> 
> I enjoyed Jon Berndt's recent posting of the mosic of the earth at night
> wrapped around a sphere, so I went off to see what else is new NASA and
> GSFC. I stumbled across this image and, when I took a look a the 3Kx3K TIFF
> version, I realized it might benefit a number of people who have been trying
> to do accurate earth renderings. In particular, the atmospheric effects at
> the edges of the earth are rather nicely done. This image is, as the
> accompanying text on the Web site
> http://rsd.gsfc.nasa.gov/rsd/bluemarble/index.html explains, a compilation
> of satellite imagery and data. The large TIFF version is about 13Mb, but the
> details are astounding.

	Yes but they don't give the raw image. Those bastards! Hope their name
is Kenny.

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It's a work of art.  Literally.
I read the pdf file telling how it was done and there's quite a bit of manipulation on
the satellite imagery
which was used.  The yellow to green colors for vegetation amounts for example, and
the surface feature relief
being 50 X so that it showed.
It's a striking picture anyhow, Earth always is to me.

Bob

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Even when you do come across images that are suitable for mapping onto a
sphere, they're usually preprocessed to show shadows, rather than as an
actual heightfield. You can see how the shadows in the upper right of the
earth are very pronounced, where the lighting should in fact be pretty flat.
It still gives a good illusion of reality, but it's even better when we
POV'ers can get our hands on the real raw data and not preprocessed images.
That's why I thought Jon Berndt's find was so cool - the lights at night
render well without artificial shadows. I only wish I could find the TIFF
version without the JPEG artifacts :(

"Matt Giwer" <jul### [at] ijnet> wrote in message
news:3A25A1D7.C20D63C3@ij.net...
> Dave Cook wrote:
> >
> > I enjoyed Jon Berndt's recent posting of the mosic of the earth at night
> > wrapped around a sphere, so I went off to see what else is new NASA and
> > GSFC. I stumbled across this image and, when I took a look a the 3Kx3K
TIFF
> > version, I realized it might benefit a number of people who have been
trying
> > to do accurate earth renderings. In particular, the atmospheric effects
at
> > the edges of the earth are rather nicely done. This image is, as the
> > accompanying text on the Web site
> > http://rsd.gsfc.nasa.gov/rsd/bluemarble/index.html explains, a
compilation
> > of satellite imagery and data. The large TIFF version is about 13Mb, but
the
> > details are astounding.
>
> Yes but they don't give the raw image. Those bastards! Hope their name
> is Kenny.

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Dave Cook wrote:
> 
> Even when you do come across images that are suitable for mapping onto a
> sphere, they're usually preprocessed to show shadows, rather than as an
> actual heightfield. You can see how the shadows in the upper right of the
> earth are very pronounced, where the lighting should in fact be pretty flat.
> It still gives a good illusion of reality, but it's even better when we
> POV'ers can get our hands on the real raw data and not preprocessed images.
> That's why I thought Jon Berndt's find was so cool - the lights at night
> render well without artificial shadows. I only wish I could find the TIFF
> version without the JPEG artifacts :(

	I agree with all that and the one used appeared to be from equatorial
orbit and faked to expand the poles to mercator projection and then put
back again for the image. 

	But as to light, I am finding that problem in POV where effectively
infinite light sources do not illuminate half a sphere. It is probably
something in the pixel resolution issue. By that I mean the larger the
rendering (4 million by 3 million pixels and up) the closer the dividing
line gets to half and half light and dark. 

	As to TIFF without JPG artifacts, I would rather wish people would
learn how to us JPEG compression. I don't mean to be obnoxious but I
spent my time in hell learning how to use it and I have seen the results
of others who have also. And it is not helped by JPEG compression ratio
being a meaningless number. 

	Look at the largest night time image and see the "dark" Sahara is
generally purplish. 

> "Matt Giwer" <jul### [at] ijnet> wrote in message
> news:3A25A1D7.C20D63C3@ij.net...
> > Dave Cook wrote:
> > >
> > > I enjoyed Jon Berndt's recent posting of the mosic of the earth at night
> > > wrapped around a sphere, so I went off to see what else is new NASA and
> > > GSFC. I stumbled across this image and, when I took a look a the 3Kx3K
> TIFF
> > > version, I realized it might benefit a number of people who have been
> trying
> > > to do accurate earth renderings. In particular, the atmospheric effects
> at
> > > the edges of the earth are rather nicely done. This image is, as the
> > > accompanying text on the Web site
> > > http://rsd.gsfc.nasa.gov/rsd/bluemarble/index.html explains, a
> compilation
> > > of satellite imagery and data. The large TIFF version is about 13Mb, but
> the
> > > details are astounding.
> >
> > Yes but they don't give the raw image. Those bastards! Hope their name
> > is Kenny.

-- 
Palm Beach Democrats are Gorons. 
	-- The Iron Webmaster, 340

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In article <3A272605.9820D87D@ij.net>, Matt Giwer <jul### [at] ijnet> 
wrote:

> 	But as to light, I am finding that problem in POV where effectively
> infinite light sources do not illuminate half a sphere. It is probably
> something in the pixel resolution issue. By that I mean the larger the
> rendering (4 million by 3 million pixels and up) the closer the dividing
> line gets to half and half light and dark. 

Try using a more distant light(how distant *is* your light?) or the 
parallel lights in MegaPOV.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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