Geodesic Lines of the Revolution Ellipsoid ( Spanish version)


Program objectives

This computer program has been developed to calculate the geodesic lines of the revolution ellipsoid, defined by the Geodetic Reference System of 1980 (GRS80). The geodesic lines are computed for two points over this ellipsoid. The distance and the azimuth for each geodesic are also computed. The distance between the two points that define this geodesic, is computed along this path. The azimuth is also computed for these two points as the angle, measured from North and clockwise, between the meridian passing by the first point and the geodesic, which connects the first and the second points.


Program description

The geodesic program is enclosed into a ZIP file named "geodesic.zip". When you have got the ZIP file and you have uncompressed this file, you have the files named geodesic.exe and input.dat. The file geodesic.exe contains a program (in FORTRAN code for PC) to calculate the geodesic lines, for two points over the revolution ellipsoid, defined by the Geodetic Reference System of 1980 (GRS80). The file named input.dat is an ASCII file with the latitude and longitude of the computation points. At the final of the computation, we obtain a new file named output.dat which contains the distance (in km) and the azimuth (in degrees), for the geodesic lines that connect the points listed in the file input.dat. These geodesic lines are enclosed into the files named geodesic_001.dat to geodesic_nnn.dat, where nnn is the number of the pairs of points enclosed in the file input.dat. The program also computes the circle arc that connects the first and the second points of each pair of points, to compare with the geodesic line. The circle arcs are enclosed into the files named circle_arc_001.dat to circle_arc_nnn.dat, where nnn is the number of the pairs of points enclosed in the file input.dat. The file input.dat has the format:

LAT1, LONG1, LAT2, LONG2
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .

LAT1, LONG1 = Geographical coordinates of the first point of the pair, latitude in degrees (north positive) and longitude in degrees (east positive).
LAT2, LONG2 = Geographical coordinates of the second point of the pair, latitude in degrees (north positive) and longitude in degrees (east positive).