Alex Stapleton wrote:
2008/7/16 Jeff Whitaker <jswhit@...146...>:
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 pltmap = 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
CairoWhat 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
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Jeffrey S. Whitaker Phone : (303)497-6313
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