Compute the centerlines following Kienholz et al., (2014).
They are then sorted according to the modified Strahler number: http://en.wikipedia.org/wiki/Strahler_number
heads : list, optional
list of shpg.Points to use as line heads (default is to compute them like Kienholz did)
Files writen to the glacier directory:
A list of
Centerlineinstances, sorted by flow order.
A netcdf file containing several gridded data variables such as topography, the glacier masks and more (see the netCDF file metadata).