Isovist

From PlanningWiki

An isovist is either the area visible from a location in a plan in two dimensions, or the visible polyhedron surrounding a location in three dimensions. It is used by architects and planners for the analysis of buildings and urban areas, typically as one of a series of methods used in space syntax.

It is similar to the concept of a viewshed in the field of geographic information science, although viewer height is not usually included.