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Input: Address, City, State/Province, Country of points A & B
Output: Addresses = Global Positions > Distance between two points = As the crow flies
great circle mapper
http://gc.kls2.com/
it helps if you know your airport codes [mihali, Sep 06 2002]
[link]
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Erm? Is this deliberately vague so that people will suggest what they think you mean and then you say..."That's it!"? |
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If so...Is this meant to be some kind of GPS add on that does the vector mathmatics of subtracting A^ from B^ and then accounting for curvature of the Earth to output a distance and direction? |
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Or just a reminder of the definition of the phrase "as the crow flies"? |
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I would call this device a 'human'.
Input to 'human'= a decent atlas, a ruler, and an understanding of how map scales work.
Output from 'human'= fairly rapid deduction of shortest distance between two points. At worst some scribbling to be undertaken on napkin or convinient back of envelope . |
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This can be acheived in UK using the PAF (Postcode Address File) available (at great cost) from the Post Office. Each UK postcode (there are ~1.7 million) has an associated X- and Y- grid reference, so with a bit of Pythagoras the distances between any two addresses can be calculated.
For non-crow distances, there are several products out there (MapInfo's Drive-Time springs to mind) which take account of annoying details like roads.
I assume that all countries have their own equivalents of PAF; I know that USA, Canada and Australia have. |
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Point A to Point B - is there a generator/translator that does this on the web? |
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tw: try the great circle mapper (see link). you just enter the airport codes of the cities invovlved, and it gives you the distance between. i think you can also input co-ordinates of some kind, but i'm not sure. i'm a little new to it myself. |
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<after some browsing...> from the great circle mapper: |
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Is there a simple way to compute great circle distances? |
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Assuming Earth is a perfect sphere of radius 6371.2 km, convert longitude and latitude to radians (multiply by pi/180), then compute as follows: |
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theta = lon2 - lon1
dist = acos(sin(lat1) × sin(lat2) + cos(lat1) × cos(lat2) × cos(theta))
if (dist < 0) dist = dist + pi
dist = dist × 6371.2
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The resulting distance is in kilometers. lon=longitude, lat=latitude |
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Can't you just tie some string to a crow, and try it out for real? |
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Autoroute 2000 can do this to +/- 1km for most of Europe. I think it uses the WGS84 GEoid (same as for GPS) so it's pretty accurate. So I guess this is Baked. |
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Kewell - I'll leave this up long enough for anybody to take advantage of the links. My search apparently used wrong terminology. Thanks (Don't understand why such an idea would get a fishbone - jealousy, perhaps - yeah, that's it - jealous, jealous, jealous) |
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all around us are little green men. |
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