Alex Stapleton wrote:
> 2008/7/16 Jeff Whitaker <[EMAIL PROTECTED]>:
>
>> Alex Stapleton wrote:
>>
>>> Not sure if this is the right place to send this, can't seem to find a
>>> dedicated bugs list or issue tracker. Or much discussion regarding the
>>> basemap toolkit at all really.
>>>
>>> Trying to savefig some Basemap instances causes the following
>>> exception in the Cairo backend. Seems to work alright using the Agg
>>> backend but the fill doesn't seem to come out properly. The sea gets
>>> colored as well as the continents.
>>>
>>> Traceback (most recent call last):
>>> File "map.py", line 48, in <module>
>>> plt.savefig("map.png", dpi=100)
>>> File "/usr/lib/python2.5/site-packages/matplotlib/pyplot.py", line
>>> 286, in savefig
>>> return fig.savefig(*args, **kwargs)
>>> File "/usr/lib/python2.5/site-packages/matplotlib/figure.py", line
>>> 1033, in savefig
>>> self.canvas.print_figure(*args, **kwargs)
>>> File "/usr/lib/python2.5/site-packages/matplotlib/backend_bases.py",
>>> line 1301, in print_figure
>>> **kwargs)
>>> File
>>> "/usr/lib/python2.5/site-packages/matplotlib/backends/backend_cairo.py",
>>> line 406, in print_png
>>> self.figure.draw (renderer)
>>> File "/usr/lib/python2.5/site-packages/matplotlib/figure.py", line
>>> 833, in draw
>>> for a in self.axes: a.draw(renderer)
>>> File "/usr/lib/python2.5/site-packages/matplotlib/axes.py", line 1539, in
>>> draw
>>> a.draw(renderer)
>>> File "/usr/lib/python2.5/site-packages/matplotlib/patches.py", line
>>> 285, in draw
>>> renderer.draw_path(gc, tpath, affine, rgbFace)
>>> File
>>> "/usr/lib/python2.5/site-packages/matplotlib/backends/backend_cairo.py",
>>> line 140, in draw_path
>>> raise ValueError("The Cairo backend can not draw paths longer than
>>> 18980 points.")
>>> ValueError: The Cairo backend can not draw paths longer than 18980 points.
>>>
>>> Here's a short reduction
>>>
>>> import matplotlib
>>> matplotlib.use("Cairo")
>>> from mpl_toolkits.basemap import Basemap
>>> import matplotlib.pyplot as plt
>>>
>>> map = Basemap(projection='ortho',
>>> llcrnrlon=-12.7, llcrnrlat=49,
>>> urcrnrlon=4.7, urcrnrlat=61,
>>> lat_0 = 50, lon_0 = 0,
>>> lat_ts=50,
>>> resolution='i')
>>> map.drawcoastlines(linewidth=0.5)
>>> map.drawcountries(linewidth=0.5)
>>> map.drawstates(linewidth=0.5)
>>> map.drawmapboundary()
>>> plt.savefig("map.png", dpi=100)
>>>
>>>
>>>
>> Alex: I don't have the Cairo backend installed, but I bet it would work if
>> you changed resolution='i' to resolution='l'. Seems like a pretty severe
>> limitation of the backend though.
>>
>> -Jeff
>>
>
> I suppose it's not up to matplotlib to work around silly limits in
> Cairo :) What about the fill issue with the Agg backend when doingfil
> zoomed in ortho maps? Am I doing something wrong?
>
Alex: I see in the example you sent that the whole map gets filled when
the fillcontinents method is used. Is this what you mean? There's a
KNOWN_BUGS file with this entry:
* The fillcontinents method doesn't always do the right thing. Matplotlib
always tries to fill the inside of a polygon. Under certain situations,
what is the inside of a coastline polygon can be ambiguous, and the
outside may be filled instead of the inside. To trigger this,
run the garp.py example with lon=-71,lat=-33 (Santiago, Chile).
Workaround - mask the land areas with the drawlsmask method instead of
filling the coastline polygons.
Using the orthographic projection to plot a local region is probably not
the best idea though - it's really intended for the global domain to
mimic what a satellite would see. I'd try the transverse mercator
('tmerc' - as in the highres.py example), or lambert conformal ('lcc')
instead. The fillcontinents method does the right thing in both cases
with your map region.
BTW: lat_ts doesn't do anything for projection='ortho'.
-Jeff
--
Jeffrey S. Whitaker Phone : (303)497-6313
NOAA/OAR/CDC R/PSD1 FAX : (303)497-6449
325 Broadway Boulder, CO, USA 80305-3328
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