Viewscape | 1. Compute viewshed | 1.1 Compute single viewshed | 1.2 Subset viewshed using by specifying the field of view | 1.3 Compute visual magnitude | 1.4 Compute the viewshed for multiple viewpoints | 2. Calculate viewscape metrics | 2.1 Calculate the metrics of viewshed | 2.2 Calculate land use/cover diversity | 2.3 calculate a single feature