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## matplotlib-users

 [Matplotlib-users] projected coordinates: Basemap vs. Proj From: Timothy W. Hilton - 2010-05-04 21:08:03 Hello matplotlib users, I am having trouble understanding the coordinate transformations in Basemap and pyproj. I have gridded MODIS vegetation data, with upper left corner and lower right corner given in projection coordinates (meters). I want to contour the data with Basemap. The data are in a sinusoidal projection, but the coordinates do not correspond to what Basemap seems to expect. The code below illustrates the problem. Proj translates the upper left to lat/lon correctly (-92.327237416031437, 30.141972433747089), while Basemap does not. #-------- code -------- from mpl_toolkits.basemap import Basemap from mpl_toolkits.basemap import pyproj ulm = [-8895604.1573329996, 3335851.5589999999] #upper left, meters lrm = [-7783653.6376670003, 2223901.0393329998] #lower right, meters sinu = pyproj.Proj(proj='sinu', lon_0=0.0, x_0=0.0, y_0=0.0) m = Basemap(projection='sinu', resolution=None, lon_0=0.0) print "ULM: " + str(ulm) print "Proj: " + str(sinu(ulm[0], ulm[1], inverse=True)) print "Basemap: " + str(m(ulm[0], ulm[1], inverse=True)) #----- end code -------- This gives: ULM: [-8895604.1573329996, 3335851.5589999999] Proj: (-92.327237416031437, 30.141972433747089) Basemap: (-159.99950210056144, -59.99995206181125) I'm sure I'm missing something really simple, but I've read a lot of documentation and I'm not sure what. Many thanks for any help. Best, Tim -- Timothy W. Hilton PhD Candidate, Department of Meteorology The Pennsylvania State University 503 Walker Building, University Park, PA 16802 hilton@...