My rendition, following Matt Giwer.
This is what I mentioned before that I had done a while back.  By using a
gradient pigment pattern for masking, in order to block the underlying overly
luminous night-lights map (this has that JPL one replacing the other wrongly
scaled map I had used before), placed under a slightly transparent surface
image map which in this animation is the darkened oceans by someone around
here.  Sorry, I forget the name and I don't want to guess wrong.
Not any easier to explain than that.
I was adjusting some on this while I had it out of mothballs anyhow and I
didn't get the shadow line exactly as I wanted but I had to give up and get
this over with for now.
Added note:  this might be difficult to discern well unless you either turn off
the room lights (at night anyway) or play full screen, or both.  Fast and
small.

Bob
--
omniVerse http://users.aol.com/persistenceofv/all.htm

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Attachments:
Download 'e@dn.mpg' (297 KB)

Another winner.

I notice a tendency for folks to model both the earth and the terminator
line as vertical.  While it is an accurate representation twice a year
(spring and fall equinox?) I think it might be more interesting to look at
the earth in mid-summer.  Try tipping the earth's main axis by 23 degrees or
so (hope I got that angle right) to illustrate things like why the sun
doesn't set above the arctic circle in the summer.  Just a thought.

Nice movie.


"Bob H."
<per### [at] aolcom?subject=PoV-News:%20&body=Relating%20to%20POV-Ray:>
wrote in message news:3a2c833e@news.povray.org...
> My rendition, following Matt Giwer.
> This is what I mentioned before that I had done a while back.  By using a
> gradient pigment pattern for masking, in order to block the underlying
overly
> luminous night-lights map (this has that JPL one replacing the other
wrongly
> scaled map I had used before), placed under a slightly transparent surface
> image map which in this animation is the darkened oceans by someone around
> here.  Sorry, I forget the name and I don't want to guess wrong.
> Not any easier to explain than that.
> I was adjusting some on this while I had it out of mothballs anyhow and I
> didn't get the shadow line exactly as I wanted but I had to give up and
get
> this over with for now.
> Added note:  this might be difficult to discern well unless you either
turn off
> the room lights (at night anyway) or play full screen, or both.  Fast and
> small.
>
> Bob
> --
> omniVerse http://users.aol.com/persistenceofv/all.htm
>
>
>
>

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Spock wrote:
> 
> Another winner.
> 
> I notice a tendency for folks to model both the earth and the terminator
> line as vertical.  While it is an accurate representation twice a year
> (spring and fall equinox?) I think it might be more interesting to look at
> the earth in mid-summer.  Try tipping the earth's main axis by 23 degrees or
> so (hope I got that angle right) to illustrate things like why the sun
> doesn't set above the arctic circle in the summer.  Just a thought.

	Well taken. 

-- 
1998: Archaeologist identifies Wailing Wall as the wall of 
a 17th century cemetery. 
1998 + 2 seconds:  his permit is pulled. So sacred the myth. 
	-- The Iron Webmaster, 182

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"Matt Giwer" <jul### [at] ijnet> wrote in message news:3A2D1770.61C24939@ij.net...
> Spock wrote:
> >
> > I notice a tendency for folks to model both the earth and the terminator
> > line as vertical.  While it is an accurate representation twice a year
> > (spring and fall equinox?) I think it might be more interesting to look at
> > the earth in mid-summer.  Try tipping the earth's main axis by 23 degrees
or
> > so (hope I got that angle right) to illustrate things like why the sun
> > doesn't set above the arctic circle in the summer.  Just a thought.
>
> Well taken.

It would have been :-) were it not for this being the result of aligning (no
pun intended) the two image maps and two gradient masking textures.  I realize
you can't see Europe much at all because of this vantage point.  Luckily there
isn't anything near the South Pole so a view from over the Tropic of Cancer
demarcation line at 23.5 degrees north of the equator would be better.

Bob H.

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"Bob H." wrote:
> 
> "Matt Giwer" <jul### [at] ijnet> wrote in message news:3A2D1770.61C24939@ij.net...
> > Spock wrote:
> > >
> > > I notice a tendency for folks to model both the earth and the terminator
> > > line as vertical.  While it is an accurate representation twice a year
> > > (spring and fall equinox?) I think it might be more interesting to look at
> > > the earth in mid-summer.  Try tipping the earth's main axis by 23 degrees
> or
> > > so (hope I got that angle right) to illustrate things like why the sun
> > > doesn't set above the arctic circle in the summer.  Just a thought.
> >
> > Well taken.
> 
> It would have been :-) were it not for this being the result of aligning (no
> pun intended) the two image maps and two gradient masking textures.  I realize
> you can't see Europe much at all because of this vantage point.  Luckily there
> isn't anything near the South Pole so a view from over the Tropic of Cancer
> demarcation line at 23.5 degrees north of the equator would be better.

	That sounds a bit like what I did in my animation above. I can give
them both a tilt after rotating. I'll give it a try. should work. 

	BTW: Mine started as three separate lays for the lit side. I overlayed
then and flattened them. They render much faster that way and nothing is
lost as you still have your original layers. 

-- 
If drugs are as bad as they say there is nothing
the law can do to a user that is worse. 
	-- The Iron Webmaster, 97

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I put the latest version of mine at:
http://members.aol.com/persistenceofv/Earth_Day-Night.mpg
Hope you will like it, tilt and all.  I could adjust on it forever as with
everything else so I stopped at a point.

Bob H.

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Looks good to me, but I'm not 100% sure about the whole tilt thing.

Its been a long time since I looked into this, but I think it goes something
like this:

- The earth goes around the sun on the "solar plane".  Most illustrations
show the camera on this solar plane so the light strikes the earth at 90
degrees and the terminator is vertical.

- The earth rotates about its axis (north pole to south pole), but this axis
is about 23.5 degrees off vertical.

- The earth's rotational axis always points in the same direction (i.e.
towards the north star) so the earth does not wobble as it goes around the
sun.

- If you combine all of these you get seasons.  I have attached a bitmap
illustrating summer in the northern hemisphere.  Six months later the light
would be coming from the other side and you would have summer in Australia.

I hope this makes sense and that I got my facts generally correct.

BTW, nice image... don't give up yet :-)


"Bob H."
<per### [at] aolcom?subject=PoV-News:%20&body=Relating%20to%20POV-Ray:>
wrote in message news:3a2f10f2@news.povray.org...
> I put the latest version of mine at:
> http://members.aol.com/persistenceofv/Earth_Day-Night.mpg
> Hope you will like it, tilt and all.  I could adjust on it forever as with
> everything else so I stopped at a point.
>
> Bob H.
>
>

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Attachments:
Download 'earth.bmp.dat' (9 KB)

"Spock" <spo### [at] nospamcom> wrote in message news:3a2fb0c1@news.povray.org...
> Looks good to me, but I'm not 100% sure about the whole tilt thing.

Thanks, but it's only for show :-) not meant to be "100%" astronomically
correct.  I put the Sun at -23.5 and the camera at +23.5 degrees.  The
rotations are: once for the camera, twice for the Earth.  That way it shows a
lot of the surface at both night and day.  The gradient masking textures are
stationary, as is the Sun.

Bob H.

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