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
ยทยทยท
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Timothy W. Hilton
PhD Candidate, Department of Meteorology
The Pennsylvania State University
503 Walker Building, University Park, PA 16802
hilton@...3085...