Longitude/ latitude to cartesian coordinates

Apr 28, 2012 at 4:21pm
Hello,

I have a file consist of some latitude/ longitudes and am looking forward to converting those geographical coordinates to cartesian coordinates. Has anyone any experience on this issue ?. There are plenty of scripts that convert the UTM format to cartesian coordinates, however, there are lack of scripts for converting latitude/longitude to cartesian coordinates...

Thanks in advance,
A
Apr 28, 2012 at 7:12pm
What is the origin and unit vectors of the coordinate system?
Apr 28, 2012 at 7:24pm
What do you mean ???
Apr 29, 2012 at 12:09pm
To make it clear I want to know if you just want to convert a latitude(-90° to 90°) and a longitude(-180° to 180°) into coordinates in a 3D space where the origin is the center of the earth of radius r.
I this case this should work:
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x = r * cos(latitude) * cos(longitude);
y = r * cos(latitude) * sin(longitude);
z = r * sin(latitude);
Last edited on Apr 29, 2012 at 12:09pm
Apr 29, 2012 at 12:35pm
This is accepted with the approximation that the earth is really a sphere. Realistically, the earth is a ellipsoid, and r is different for each compnent; i.e.,

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x = a * sin(theta) * cos(phi);
y = b * sin(theta) * sin(phi);
z = c * cos(theta);


Your conversion is simply from spherical coordinates to cartesian coordinates. Refer to wikipedia for more information. You have to be good in trigonometric identities to do the conversions for earth.

http://en.wikipedia.org/wiki/Spherical_coordinate_system
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