Isovist integration can loosely refer to a normalised (inverse) measure of the mean shortest path from one point to all other points in the system.
Isovist integration
Sources
Turner, A. & Penn, A. (1999), Making Isovists Syntactic: Isovist Integration Analysis, In Proceedings of the 2nd International Space Syntax Symposium, Universidade de Brasilia, Brazil, 1-9. pp.3