The Viable Interior Index is the area of the polygon that is not in the edge-disturbance zone. The index is normalized using the Equal Area Circle (EAC) as follows...

The Viable Interior Index is appropriate to use when...

- the analysis requires the area of the polygon that is insulated from the external environment
- the width of the edge disturbance zone is known
- a measure of compactness is needed

Viable Interior Index results for select shapes...