All of the local isovist measures are calculated using a ‘radial scan’ algorithm. For every analysis point in the subject area, a single isovist ‘radial’ is traced, from the point ‘origin’ coordinates, to the coordinates of the nearest ‘intersection’ with a drawing segment in a certain direction.
Above: Local radial scanning resolving Connectivity in Mies’ Barcelona Pavilion
Over time, the angle of the radial from each point is varied by a small stochastic amount. Doing so results in a continual circular ‘scan’ of radial samples. The incremental radial intersection information is then used to refine calculation of the isovist measure values at each point. A single ‘local sample’ is counted each time that all points complete a full 360-degree radial sweep. As local samples accrue, the stochastic variation of radial angle negates angular resolution related inaccuracies in the results.