topic Re: From Decimal degrees to meter in Geoprocessing Questions

From Decimal degrees to meter

KasperSmith_Larsen — Sun, 24 Aug 2014 13:28:36 GMT

Hey Guys

I have a data set Air mass trajectories (excel file) with a lot of points given in decimal degrees. I have plotted the trajectories in Arcmap but I need to know the distance between them. They span more or less from equator to Greenland so there is the issue of different E/W distances.

Regards Kasper

Re: From Decimal degrees to meter

DanPatterson_Retired — Sun, 24 Aug 2014 14:18:40 GMT

I don't work with data covering such a large area, but I would suggest km...in any event you probably want the geodesic distances which have new options in 10.2.1 perhaps using the Near tool

Re: From Decimal degrees to meter

stefanstamenov — Sun, 24 Aug 2014 14:51:06 GMT

converting decimal degrees to miles, kilometers,

Re: From Decimal degrees to meter

stefanstamenov — Sun, 24 Aug 2014 14:54:02 GMT

This must work, though I never used it

Latitude/Longitude Distance Calculator

Re: From Decimal degrees to meter

BruceHarold — Mon, 25 Aug 2014 16:16:24 GMT

If you do not have Desktop Advanced and the Near GP tool then provided you can deal with 0.5% error then the Haversine formula might be suitable.

Or Vincenty if you want to get fancy.

Re: From Decimal degrees to meter

KasperSmith_Larsen — Mon, 25 Aug 2014 20:38:00 GMT

Thanks for your answers.

I have tried using the Haversine formula in excel but I can’t get the right distance. I have calculated the following parameter:

R = earth’s radius (mean radius = 6,371km)
Δlat = lat₂− lat₁
Δlong = long₂− long₁
a = sin²(Δlat/2) + cos(lat₁)cos(lat₂)sin²(Δlong/2)
c = 2*atan2(√a, √(1−a))
d = R*c (distance)

As described at http://www.ig.utexas.edu/outreach/googleearth/latlong.html

It says on the web-site that angles need to be in radians and I tried with radians calculated from both decimal degrees and degrees, minutes, seconds.

Re: From Decimal degrees to meter

BruceHarold — Mon, 25 Aug 2014 20:42:52 GMT

I think Excel does something unusual with ATAN2.

Lat/Lon Distance Excel (Spherical Law of Cosines and Haversine Formula in Excel) | feed on my links

Re: From Decimal degrees to meter

KasperSmith_Larsen — Tue, 26 Aug 2014 10:28:08 GMT

Now I got the Haversine fomula to work so problem solved

Thanks to all of you for your input they really helped.