def pyplot_draw_point_cloud(points, output_filename):
    """ points is a Nx3 numpy array """
    import matplotlib.pyplot as plt
    fig = plt.figure()
    ax = fig.add_subplot(111, projection='3d')
    ax.scatter(points[:, (0)], points[:, (1)], points[:, (2)])
    ax.set_xlabel('x')
    ax.set_ylabel('y')
    ax.set_zlabel('z')
