chuckr30 Posted February 14, 2007 Share Posted February 14, 2007 Hi, if I have 2 lat/long pairs, how do I determine the distance between the 2 points in feet? I would prefer a spreadsheet but a Win XP program would be fine too. Quote Link to comment
+surferacf Posted February 14, 2007 Share Posted February 14, 2007 GOOGLE EARTH Quote Link to comment
+poohstickz Posted February 14, 2007 Share Posted February 14, 2007 (edited) Hi, if I have 2 lat/long pairs, how do I determine the distance between the 2 points in feet? I would prefer a spreadsheet but a Win XP program would be fine too. Use the great circle distance between two points. Two good references are wikipedia and the whizzo bang aviation formulary In Java, for example: double d = Math.acos(Math.sin(lat1) * Math.sin(lat2) + Math.cos(lat1) * Math.cos(lat2) * Math.cos(lon1 - lon2)); Where the units are in radians; Real men don't use feet -- There's an obscure application called Google that you can use to find out how to convert to other units but, generally, you pretend to be at the equator (approximately 6378137 metres, captain). Edit: I just noticed that the aviation formulary page actually does have an Excel spreadsheet.. Edited February 14, 2007 by poohstickz Quote Link to comment
+StarBrand Posted February 14, 2007 Share Posted February 14, 2007 Use fizzymagic's GeoCalc program Quote Link to comment
+Gator Man Posted February 14, 2007 Share Posted February 14, 2007 Here's what I use! http://jan.ucc.nau.edu/~cvm/latlongdist.html Quote Link to comment
+DonB Posted February 15, 2007 Share Posted February 15, 2007 Free software: http://davidbray.org/mobile Quote Link to comment
b_storch Posted February 15, 2007 Share Posted February 15, 2007 Plot them on a map and use the scale at the bottom. Quote Link to comment
+Mudfrog Posted February 16, 2007 Share Posted February 16, 2007 If you don't think they are too far from each other and you have a mapping GPSr, input both sets of coordinates into it. Then go to the map page and measure the distance between them. Quote Link to comment
+Waterboy Posted February 16, 2007 Share Posted February 16, 2007 Since you are asking for the calculations in feet, I assume that you are talking short distances, less than two miles. A set of equations that you could use for a spherical approximation follow: L1 = Latitude of Point 1 λ1 = Latitude of Point 1 L2 = Latitude of Point 2 λ2 = Latitude of Point 2 The distance north/south in feet will be: ΔL = 364566*( L1 - L2 ) The distance east/west in feet will be: Δλ = 364566*( λ1 - λ2 )*cos(( L1 + L2 )/2) Using the Pythagorean Theorem the distance may now be calculated as: Dist = SQRT(ΔL*ΔL + Δλ*Δλ) Notes: 1. Coordinates should be expressed in decimal degree format. 2. This method will give you fairly accurate results on distances up to 10 miles. 3. These calculations should not be used if you are caching in extreme polar coordinates, like latitudes above 87º. 4. Despite what you may read in these forums no system of distance calculation is completely accurate, surveyors have compared them to actual measured conditions. There are some methods of calculation that the error is less than one part in ten thousand. 5. If you understand what I wrote above, it should be no problem putting it on a spreadsheet. However, it will take time. Be careful on using the correct format on all angles. 6. You may find it easier if you use UTM coordinates. Although accuracy using these coordinates drops as you approach a different zone (at Longitudes of -72º, -78º, -84º, -90º, -96º,…..). It would also be inaccurate in extreme polar coordinates. Quote Link to comment
+naviguesser74 Posted February 17, 2007 Share Posted February 17, 2007 send me an email and i'll send you an excel spreadsheet that calculates direction and distance between two lats and longs. jeffreyfort@mac.com Quote Link to comment
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