demo_basic_use.py

""" Demonstrates basic use of the hill_shade function.
"""
from __future__ import print_function
from __future__ import division

import numpy as np
import matplotlib as mpl

mpl.interactive(False) 
import matplotlib.pyplot as plt

from plotting import make_test_data, add_colorbar
from hillshade import hill_shade

def main():
    fig, axes = plt.subplots(1, 1) 
    
    # Generate terrain of 200 by 200 km, height between -2.25 and 5.7 km
    data = make_test_data('hills', noise_factor=0.05) / 2 + 2 
    print("data range: {} {}".format(np.min(data), np.max(data)))
    
    cmap=plt.cm.get_cmap('gist_earth')
    vmin, vmax = -5, 5  # scale clip color map between -5, 5
    
    rgb = hill_shade(data, terrain=data * 5, # scale terrain height to make relief visible 
                     #azimuth=90, elevation=60,        # un-comment to use non-default values
                     #ambient_weight=0, lamp_weight=5, # un-comment to use non-default values
                     cmap=cmap, vmin=vmin, vmax=vmax)
        
    axes.imshow(rgb, norm=None, origin='lower')
    add_colorbar(axes, label='Terrain height [km]', cmap=cmap, vmin=vmin, vmax=vmax)
    axes.set_xlabel('[km]')
    axes.set_ylabel('[km]')

    fig.tight_layout()
    plt.show()

if __name__ == "__main__":
    main()