calculate_distance      Sample and calculate the distance to the local
                        treeline
classify_above_treeline
                        Classify points as above or below the treeline
distance_to_treeline    Wrapper that calculates the distance relative
                        to the nearest local treeline
generate_grid           Generate a grid around the input point
generate_point_df       Generate a data frame with points above the
                        treeline
get_nearest_point       Search the nearest point in a data frame
plot_distr              Plot the sampled area
pointsAboveTreeline     Points on or above the treeline
sample_treeline         Compute the local treeline
