EDIT: I guess I’d use qGIS python bindings: http://www.qgis.org/wiki/Python_Bindings That’s the easiest way I can think of. I remember hand rolling something before, but it’s ugly. qGIS would be easier, even if you had to make a separate Windows installation (to get python to work with it) then set up an XML-RPC server to run … Read more
If you have the latest version of geopandas (0.3.0 as of writing), and the if df is a GeoDataFrame, you can use the x and y attributes on the geometry column: df[‘lon’] = df.point_object.x df[‘lat’] = df.point_object.y In general, if you have a column of shapely objects, you can also use apply to do what … Read more
Here’s my own solution, based on the idea in ask Dr. Math. I’d be happy to see your feedback. Disclaimer first. This solution is correct for spheres. Earth isn’t a sphere, and the coordinates system (WGS 84) doesn’t assume it’s a sphere. So this is just an approximation, and I can’t really estimate is error. … Read more
I ended up finding java code from IBM that solved it: http://www.ibm.com/developerworks/java/library/j-coordconvert/index.html Just for reference, here is my python implementation of the method I needed: import math def utmToLatLng(zone, easting, northing, northernHemisphere=True): if not northernHemisphere: northing = 10000000 – northing a = 6378137 e = 0.081819191 e1sq = 0.006739497 k0 = 0.9996 arc = northing … Read more
I have a very similar piece of code. It got me very close results when compared to another implementation. I think the problem with yours is that you are using “distance” as linear distance in meters instead of angular distance in radians. /// <summary> /// Calculates the end-point from a given source at a given … Read more
…sigh. Stupidity on my part. Apparently the correct order is longitude, latitude. I was fooled into thinking that both coordinates had the same range (-180 to 180) so thought something more subtle was going on.
Here’s the implementation I settled on: public static string Encode(IEnumerable<GeoLocation> points) { var str = new StringBuilder(); var encodeDiff = (Action<int>)(diff => { int shifted = diff << 1; if (diff < 0) shifted = ~shifted; int rem = shifted; while (rem >= 0x20) { str.Append((char)((0x20 | (rem & 0x1f)) + 63)); rem >>= 5; … Read more
Ok, for starters, you don’t really need to use the Haversine formula here. For large distances where a less accurate formula produces a larger error, your users don’t care if the match is plus or minus a few miles, and for closer distances, the error is very small. There are easier (to calculate) formulas listed … Read more
To elaborate on synecdoche’s answer, the SRID is sometimes called an “EPSG” code. The SRID/EPSG code is a defacto short-hand for the Well-Known-Text representations of projections. You can do a quick search on the SRID table to see if you can find an exact or similar match: SELECT srid, srtext, proj4text FROM spatial_ref_sys WHERE srtext … Read more