Hi again Jeff et al... I've had a play around with the extra few lines of code - on paper this seems like it should solve the problems I'm experiencing. However, an error's being thrown up by the transform scalar function, as my lons and lats won't necessarily be increasing. The data I'm plotting is satellite data and so at the beginning and end of the orbit file lats go over the pole from 90 to -90, with a similar problem for the lons - whereby the data is taken across the satellite track. I've thought about sorting the data before passing it to transform_scalar but I'm always going to be left with the problem in either lats or lons.
I've uploaded the file I'm currently working with this time. It's three columns of lons, lats and z values. Once again, many thanks for your help. Will. http://old.nabble.com/file/p28133659/test.plt test.plt Jeff Whitaker wrote: > > On 4/2/10 6:32 AM, Will Hewson wrote: >> This is great Jeff, thanks for the help - I'll give it a try over the >> weekend >> (it's bank holiday here in the UK!) and get back to you, if I'm still >> having >> trouble I'll stick up the plotting data too... thanks again. >> >> Will >> > > Will: I forgot to mention that contourf will work on your data without > having to interpolate to projection coordinates. > > -Jeff >> >> >> Jeff Whitaker wrote: >> >>> On 4/2/10 4:27 AM, Will Hewson wrote: >>> >>>> Hi forum/ mailing list, When I plot in the orthographic projection I'm >>>> getting the large artefact shown below extending away from the north >>>> east of the globe. I'm not finding the same problem when plotting in a >>>> full globe projection so I'm presuming the problem is with the way I'm >>>> projecting everything rather than my data itself. I've included my >>>> plotting code below, if anyone is able to spot some glaring omissions/ >>>> errors I'd be most grateful (I've been using python/ matplotlib for >>>> only a couple of weeks now!). >>>> >>> Will: I think what's happening is that pcolormesh is having trouble >>> dealing with the higher curvlinear grid, which becomes nearly >>> pathological near the horizon of the projection. If you take a look at >>> the test.py file in the basemap examples directory, you'll see an >>> example orthographic plot that solves this problem by first >>> interpolating the data to a regular grid in projection coordinates (with >>> values over the plot horizon masked). The example uses imshow, but >>> pcolormesh works as well. A standalone version of the example using >>> pcolormesah is attached, which uses data files in the basemap examples >>> directory. >>> >>> -Jeff >>> >>> from mpl_toolkits.basemap import Basemap, shiftgrid >>> import numpy as np >>> import matplotlib.pyplot as plt >>> # read in topo data (on a regular lat/lon grid) >>> # longitudes go from 20 to 380. >>> topoin = np.loadtxt('etopo20data.gz') >>> lons = np.loadtxt('etopo20lons.gz') >>> lats = np.loadtxt('etopo20lats.gz') >>> # shift data so lons go from -180 to 180 instead of 20 to 380. >>> topoin,lons = shiftgrid(180.,topoin,lons,start=False) >>> m = Basemap(projection='ortho',lon_0=-105,lat_0=40,resolution='l') >>> # transform to nx x ny regularly spaced native projection grid >>> nx = int((m.xmax-m.xmin)/40000.)+1; ny = int((m.ymax-m.ymin)/40000.)+1 >>> topodat,x,y =\ >>> m.transform_scalar(topoin,lons,lats,nx,ny,returnxy=True,masked=True,order=1) >>> # create the figure. >>> fig=plt.figure(figsize=(8,8)) >>> im = m.pcolormesh(x,y,topodat,cmap=plt.cm.jet) >>> m.drawcoastlines() >>> m.drawparallels(np.arange(0.,80,20.)) >>> m.drawmeridians(np.arange(10.,360.,30.)) >>> m.drawmapboundary() >>> plt.show() >>> >>> >>> >> > > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > > -- View this message in context: http://old.nabble.com/Basemap--orthographic-projection-plot-doesn%27t-respect-globe-boundary-tp28117654p28133659.html Sent from the matplotlib - users mailing list archive at Nabble.com. ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
