Prepare your data

You'll need to prepare your data for interpolation. The geographic coordinates should be in units other than lat/longs. If your data are referenced in lat/longs, this is one cheap and dirty way to produce coordinates that you can use in an interpolation program such as GS+:

"One second of latitude equals 30.92 meters on the ground [multiply your latitudes by 30.92]. For longitude, calculate the cosine of the latitude then multiply by 30.92 [this is the scale factor for the longitude values]." from the GS+ help files

If you know what to do from there, great: otherwise, grab me and we'll take care of rescaling your data.

If you have a shapefile of your region, and it's in lat/longs, then things get complicated. Talk to me, and we can transform it if you like. But you can skip the background map for this exercise, anyway, so it's not critical.


Website maintained by Andy Long. Comments appreciated.
aelon@sph.umich.edu