"""
# Topograpy

The Federal Office of Topography swisstopo publishes height data for all of Switzerland.
topo.zip contains two such files for the same location:

  * terrain.xyz describes the surface of the region without vegetation and buildings.
  * surface.xyz includes vegetation and buildings.

Both files cover the same 1 km2 area and contain height data on a grid with 0.5m spacing.

- Load the data using `np.loadtxt`
- reshape the data into the corect shape
- create a `contour`- or `contourf`-plot
  with the difference between terraind and surface

"""
