The Bartlett Centre for Advanced Spatial Analysis


CASA Working Paper 69


1 November 2003

A Rigorous Definition of Axial Lines: Ridges on Isovist Fields

We suggest that 'axial lines' defined by (Hillier and Hanson, 1984) as lines of uninterrupted movement within urban streetscapes or buildings, appear as ridges in isovist fields (Benedikt, 1979) as Rana first proposed (Rana, 2002). These are formed from the maximum diametric lengths of the individual isovists, sometimes called viewsheds, that make up these fields (Batty and Rana, 2004).

We present an image processing technique for the identification of lines from ridges, discuss current strengths and weaknesses of the method, and show how it can be implemented easily and effectively.

This working paper is available as a PDF. The file size is 963KB.

Authors: Rui Carvalho

Publication Date: 1/11/2003

Download working paper No. 69.