Isovist


A single isovist is the volume of space visible from a given point in space, together with a specification of the location of that point. Isovists are naturally three-dimensional, but they may also be studied in two dimensions: either in horizontal section or in other vertical sections through the three-dimensional isovist. Every point in physical space has an isovist associated with it.
The boundary-shape of an isovist may or may not vary with location in, say, a room. If the room is convex, then the boundary-shape of every isovist in that room is the same; and so is its volume. But the location of the viewpoint relative to the boundary would or could be different. However, if the room were non-convex, then there would be many isovists whose volume would be less than that of the whole room, and perhaps some that were the whole room; and many would have different, perhaps unique shapes: large and small, narrow and wide, centric and eccentric, whole and shredded.
One can also think of the isovist as the volume of space illuminated by a point source of light.
It is used in the field of architecture for analysis of buildings and urban areas, typically as one of a series of methods used in space syntax.