On 12/19/11 2:23 PM, Stefan Mertl wrote: > Hello, > > I'm starting to use the mpl_toolkits.basemap.pyproj.Proj class to do > lon/lat to UTM coordinate conversion. > I did some tests and noticed that there is a discrepancy between the > mpl_toolkits.basemap.pyproj.Proj output and the proj commandline tool > output. > > e.g.: I'm converting the coordinates lat=48.2; lon=16.5 to UTM > coordinates UTM zone 33 with WGS84 ellipse. > I'm using the following proj4 string for the conversion: > +proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m +no_defs > > The output using mpl_toolkits.basemap.pyproj.Proj is: > x: 611458.865; y: 5339596.032 > > The proj commandline tool using the same proj4 string gives: > x: 611458.69 y: 5339617.54 > > As you can see, the y coordinate differs significantly. > > Here's the code used with the basemap pyproy classes: > > -------------------------------------------------- > > from mpl_toolkits.basemap.pyproj import Proj > > # I got the proj string from > # http://spatialreference.org/ref/epsg/32633 > myProj = Proj("+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m > +no_defs") > > lat = 48.2 > lon = 16.5 > > (x,y) = myProj(lon, lat) > > print "x: %.3f; y: %.3f" % (x,y) > > --------------------------------------------------- > > Can somebody explain me this behavior? > > Regards, > Stefan. > Stefan:
When I run this test, I get the same answer with both, and it is the same as the answer basemap.pyproj gave you. I suspect you didn't install the extra datum files with your command-line proj distribution. -Jeff -- Jeffrey S. Whitaker Phone : (303)497-6313 Meteorologist FAX : (303)497-6449 NOAA/OAR/PSD R/PSD1 Email : jeffrey.s.whita...@noaa.gov 325 Broadway Office : Skaggs Research Cntr 1D-113 Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
