matplotlib-checkins Mailing List for matplotlib

Revision: 6705
 http://matplotlib.svn.sourceforge.net/matplotlib/?rev=6705&view=rev
Author: jswhit
Date: 2008年12月28日 16:07:10 +0000 (2008年12月28日)
Log Message:
-----------
simplify calculation of geostationary limb
Modified Paths:
--------------
 trunk/toolkits/basemap/lib/mpl_toolkits/basemap/proj.py
Modified: trunk/toolkits/basemap/lib/mpl_toolkits/basemap/proj.py
===================================================================
--- trunk/toolkits/basemap/lib/mpl_toolkits/basemap/proj.py	2008年12月26日 23:20:56 UTC (rev 6704)
+++ trunk/toolkits/basemap/lib/mpl_toolkits/basemap/proj.py	2008年12月28日 16:07:10 UTC (rev 6705)
@@ -94,20 +94,21 @@
 elif self.projection == 'geos':
 self._proj4 = pyproj.Proj(projparams)
 # find major and minor axes of ellipse defining map proj region.
- delta = 0.01
- lats = np.arange(0,90,delta)
- lon_0 = projparams['lon_0']
- lons = lon_0*np.ones(len(lats),'d')
- x, y = self._proj4(lons, lats)
- yi = (y > 1.e20).tolist()
- ny = yi.index(1)-1
- height = y[ny]
- lons = np.arange(lon_0,lon_0+90,delta)
- lats = np.zeros(len(lons),'d')
- x, y = self(lons, lats)
- xi = (x > 1.e20).tolist()
- nx = xi.index(1)-1
- width = x[nx]
+ # h is measured from surface of earth at equator.
+ h = projparams['h'] + self.rmajor
+ # latitude of horizon on central meridian
+ lonmax = 90.-(180./np.pi)*np.arcsin(self.rmajor/h)
+ # longitude of horizon on equator
+ latmax = 90.-(180./np.pi)*np.arcsin(self.rminor/h)
+ # truncate to nearest hundredth of a degree (to make sure
+ # they aren't slightly over the horizon)
+ latmax = int(100*latmax)/100. 
+ lonmax = int(100*lonmax)/100. 
+ # width and height of visible projection
+ P = pyproj.Proj(proj='geos',a=self.rmajor,\
+ b=self.rminor,lat_0=0,lon_0=0,h=projparams['h'])
+ x1,y1 = P(0.,latmax); x2,y2 = P(lonmax,0.)
+ width = x2; height = y1
 self._height = height
 self._width = width
 if (llcrnrlon == -180 and llcrnrlat == -90 and
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