Kriging and datum shifts
Yes Edzer, I was not using terminology accurately. Apologies, R is new to me. Let me dig deeper if this simple example is needed. I will make sure if gstat kriging methods correctly use great circle distances correctly. Jeroen
On 2013-05-28 12:15 PM, Edzer Pebesma wrote:
Jeroen, sp does not have anything to do with kriging, so your comment is confusing. sp does create spatial objects from data.frame's, and may do some sanity checks on coordinates in case they are longlat -- you have to specify they are longlat, though. If they are specified as longlat, and e.g. gstat::idw is used for interpolation, it should use great circle distances as opposed to Euclidian distances to figure out interpolation weights. If this is not the case, I'd like to look at a simple, reproducible example. Kriging on spherical data is done at your own risk, there are no checks that the variogram model can be applied sanely on a sphere, as reported before.