Vista Length (Hv) expresses the longest single view available at each location. In isovist terminology, it records the longest radial of the isovist at a location. Vista Length values identify regions of high axial view.

To determine Vista Length, the Isovist_App calculates the distances of successive radial-plan intersections from every point ‘V’ in plan. The highest distance is recorded. The outcome is an absolute value of length.

In notation form the calculation for Vista Length is expressed as: 

Where ‘Li’ is radial length.