John Burkhart wrote: > Jeff, > > Apologies for dual emails... my earlier one wasn't meant to be sent... > > I was hoping you could expand slightly (or at least provide an example) > on #1 below. As I said earlier, I now have the GEOTIFF information which > should help, and a customized version of the image without the white > space. Next, is just to get the raw data! Probably easier - but it seems > this is a good exercise nevertheless. > > Regards, > john
John: It would definitely be easier to have the raw data. Regarding step number 1, you can do something like this # m1 is the Basemap instance for map projection 1 (the original # projection that the GEOTIFF image is in) # m2 is the Basemap instance for map projection 2 (what you want # to interpolate the image to) # x2,y2 are the map projection coordinates of the m2 grid. lons2, lats2 = m2(x2, y2, inverse=True) # x2, y2 must be 2d arrays # x1, y1 is the m2 grid in m1 coordinates. x1, y1 = m1(lons2, lat2) # if x,y are 1d arrays defining the m1 grid, and data1 is the data on # the m1 grid, here's how to interpolate to the m2 grid. # data2 is now data1 interpolated to the m2 grid. data2 = interp(data1,x,y,x1,y1) -Jeff > >> >> If your image had no borders of annotations, you could read it in and >> get the RGB values of each pixel using PIL (following the example in >> warpimage.py). You could then >> >> 1) compute the polar stereographic coordinates of the rectilinear grid >> you want to interpolate to >> >> 2) use the interp function to interpolate the RGB values from the >> original polar stereographic grid to the new grid. >> >> Here's part of the docstring for the interp function: >> >> def >> interp(datain,xin,yin,xout,yout,checkbounds=False,masked=False,order=1): >> """ >> dataout = interp(datain,xin,yin,xout,yout,order=1) >> >> interpolate data (datain) on a rectilinear grid (with x=xin >> y=yin) to a grid with x=xout, y=yout. >> >> datain is a rank-2 array with 1st dimension corresponding to y, >> 2nd dimension x. >> >> xin, yin are rank-1 arrays containing x and y of >> datain grid in increasing order. >> >> xout, yout are rank-2 arrays containing x and y of desired output >> grid.""" >> >> Here xin and yin would be the (1d) polar stereographic coords of the >> original image grid. xout, yout would be the (2d) coordinates of the >> new grid (in the same polar stereographic coordinates as the original >> image grid, even though the new grid is a different map projection). >> >> You can use the Basemap instances defined for each projection to >> compute the coordinates of each grid, and to transform the new grid >> into the projection coordinates of the original grid. >> >> It's tricky, but should be possible if the image doesn't have any >> whitespace or annotations around the edges. Unfortunately, the image >> you point to doesn't appear to be that simple. >> >> I'm copying the matplotlib-users list just in case anyone has a better >> suggestion ... >> >> -Jeff >> >> >> >> -- >> Jeffrey S. Whitaker Phone : (303)497-6313 >> Meteorologist FAX : (303)497-6449 >> NOAA/OAR/PSD R/PSD1 Email : [EMAIL PROTECTED] >> 325 Broadway Office : Skaggs Research Cntr 1D-124 >> Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg > > > > ---------------------------------------------------------------- > This message was sent using IMP, the Internet Messaging Program. > > -- Jeffrey S. Whitaker Phone : (303)497-6313 Meteorologist FAX : (303)497-6449 NOAA/OAR/PSD R/PSD1 Email : [EMAIL PROTECTED] 325 Broadway Office : Skaggs Research Cntr 1D-124 Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
