EPSG

EPSG guidance note #7.

2002-11-22

Applies to 2D and the horizontal component of 3D ellipsoidal systems.

In the formulas that follow, the coordinate strings are symbolically represented as follows: deg decimal degrees adeg absolute value of decimal degrees ideg integer degrees sdeg signed integer degree min real-number minutes imin integer minutes sec real-number seconds lathem, lonhem hemisphere abbreviation Forward calculation from decimal degree representation to DMSH representation: adeg = ABS(deg) ideg = INT(adeg) min = (adeg - ideg) * 60 imin = INT(min) sec = (min - imin) * 60 Then for latitude, if deg < 0, lathem = S else lathem = N For longitude, if deg < 0, lonhem = W else lonhem = E Reverse calculation from DMSH representation to decimal degree representation: deg = (ideg + imin/60 + sec/3600) * H where for latitude H = 1 if lathem = N and H = -1 if lathem = S and for longitude H = 1 if lonhem = E and H = -1 if lonhem = W