I computed the convex hull for the points in paths returned by Basemap.drawcountries() and I got the attached map (convex hull algorithm: http://www.scipy.org/Cookbook/Finding_Convex_Hull). You can see the magenta convex hull polygon with U.S. border lines drawn in black as a reference.
Unfortunately, adding the coastlines to the computation of the convex hull just hungs the program.
I tried running the computation of the convex hull using the polygons retrieved from US Shapefile in http://www.geophysique.be/en/2011/01/27/matplotlib-basemap-tutorial-07-shapefiles-unleached/, but the program hungs due to the huge amount of points too.
I am running out of time to complete this project, so I cannot implement a more efficient version of the convex hull computation to include the coastlines in the process right now.
- if I plot an open path in the area next to U.S./ Mexico border and I'd like to have the filling of such path to go all the way to the border, I figured I could add extra points to close the path over Mexico in order to fill the area I need. What I do not understand is how can I mask the filled portion over Mexico without masking any portion of the filling over U.S.. i.e. the portion that is outside the polygon shown in the map attached.
- if I have similar situation in Florida, for which I would like to mask all points that are not over land using is_land() method, how can I do this ?