Hatch, Sara J wrote: > Jeff, > > My plan was to use the orthographic projection to represent the Moon (hence > the 1737.4 km radius) and to plot a spacecraft trajectory around it. If I had > read the rsphere documentation past the first half sentence I would have > noticed that it was in meters instead of kilometers, sorry about that. Once I > implemented this change, the horizontal lines go away. >
Sara: OK, great. > Regarding the origin location: I have my spacecraft trajectory calculated > with the origin being coincident with the center of the Moon. I can easily > translate my coordinates to work with the origin not being the center of the > projection, but would it be possible to implement some way to change where > the origin is on the projection? > No, sorry - there's no easy way to do that. -Jeff > Thanks, > Sara > > > > -----Original Message----- > From: Jeff Whitaker [mailto:jsw...@fastmail.fm] > Sent: Thursday, March 12, 2009 4:05 PM > To: Hatch, Sara J > Cc: matplotlib-users@lists.sourceforge.net > Subject: Re: [Matplotlib-users] Erroneous Horizontal Lines when Using Basemap > > Hatch, Sara J wrote: > >> Matplotlib Folks, >> >> I tried to use the orthographic projection in the basemap toolkit and >> I'm finding that the parallel lines are not behaving correctly, i.e., >> there are horizontal lines connecting the left and right side of the >> map boundary where a curved latitude line intersects the map boundary. >> I've included a sample script below and a figure illustrating the problem. >> >> import pylab >> >> import mpl_toolkits.basemap as basemap >> >> ortho = >> basemap.Basemap(projection='ortho',lon_0=0,lat_0=50,rsphere=1737.4) >> >> ortho.drawparallels(pylab.arange(-90,90,30)) >> >> ortho.drawmeridians(pylab.arange(0,360,30)) >> >> ortho.drawmapboundary(fill_color='w') >> >> In addition, how do I change the x/y coordinates the center of the >> projection to be (0,0)? With the above code, the center of the >> bounding circle is at (1737.4,1737.4). >> >> Thanks for the help, >> >> Sara >> >> > Sara: If you take out the rsphere=1734.4 (thereby using the default > value of 6370997), the jumpy lines go away. rsphere=1734.4 means assume > the earth is a perfect sphere with a radius of 1734.4 meters. That's an > awfully small earth - I think the jumpy lines are a result of roundoff > errors in the map projection calculation for very small spheres. Still, > that shouldn't happen, so I will look into it. > > Regarding the x/y coordinate of the middle of the plot - Basemap assigns > the lower left corner of the map projection region an x/y value of 0,0 > for most map projections. > > -Jeff > > ------------------------------------------------------------------------------ Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are powering Web 2.0 with engaging, cross-platform capabilities. Quickly and easily build your RIAs with Flex Builder, the Eclipse(TM)based development software that enables intelligent coding and step-through debugging. Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
