[R-sig-Geo] gstat distance on a non-spherical Earth?

[Martin Ivanov]

Hello,

The interpolation routines of gstat use great circle distance in km as 
units for the distance between two  points of unprojected data. My 
question is, if the datum is not a sphere, how is distance in gstat defined
for unprojected data? For example, how does gstat calculate the "great 
cirlce distance" between two points on the WGS84 datum?

Best regards,


-- 
Dr. Martin Ivanov
Eberhard-Karls-Universität Tübingen
Mathematisch-Naturwissenschaftliche Fakultät
Fachbereich Geowissenschaften
Water & Earth System Science (WESS)
Keplerstraße 17, 72074 Tübingen, Deutschland
Tel. +4970712975023