Open a raster that covers the globe and extract a subset of the raster.
import gdal
# Path to a tiff file covering the globe
# http://visibleearth.nasa.gov/view.php?id=57752
tif_name = "/path_name/land_shallow_topo_21600.tif"
# Open raster in read only mode
ds = gdal.Open(tif_n...
