Actually, i think that is rather easy to do. You just take a circle, and reproject it into your coordinate system. The radius of the circle is the earth radius, and the middlepoint is the position on the earth where the sun is in the zenith for that moment.
The only thing you need is the position of the sun. Even this one is rather easy to calculate: Around 21st of march and december is the sun in the zenith on the equator. The 21st of june is the sun in the zenith on the tropic of cancer (23°44' N) (kreeftskeerkring ;) ) and the 21st of december the sun is in the zenith on the tropic of capricorn (23°44' S) (steenbokskeerkring). The last thing there is to know is that the sun always moves between these two tropics and therefor describing a sinus. Now it's possible to create a function that describes this movement, and voila, you have your coordinates of the center of the circle! If you have any more questions, feel free to ask grtz, Wouter Schaubroeck On Tue, Apr 22, 2008 at 4:43 PM, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Anybody ever had an attempt in drawing the night area of the planet ? > > I'm trying to figure out a simple way, based on a timestamp, to darken the > area of the map representing the night. Preferably using vector data so I can > check whether it's day/night on a certain point on the planet. > > Many thanks for any clue ! > > Jan > > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by the 2008 JavaOne(SM) Conference > Don't miss this year's exciting event. There's still time to save $100. > Use priority code J8TL2D2. > > http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone > _______________________________________________ > Geotools-gt2-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users > ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Geotools-gt2-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
