$$PARA = \frac{p_{ij}} {a_{ij}}$$
where \(p_{ij}\) is the perimeter in meters and \(a_{ij}\) is the
area in square meters.
PARA is a 'Shape metric'. It describes the patch complexity in a
straightforward way. However, because it is not standarised to a certain
shape (e.g. a square), it is not scale independent, meaning that increasing
the patch size while not changing the patch form will change the ratio.
Because the metric is based on distances or areas please make sure your data
is valid using check_landscape.
Behaviour
Increases, without limit, as the shape complexity
increases.