Using Isovists in Measuring Surveillance and Expected Guardianship in Residential Neighborhood Property Crimes

Abstract

Purpose: Assessing a level of surveillability, supervision, and expected guardianship in residential neighborhoods has been a topic of interest since the early work of Jacobs’ ‘eyes on the street’, and Newman’s ‘defensible space’. This paper reports on the use of isovists (two-dimensional polygons that represent the characteristics of the visual field) in understanding incidents of ‘breaking and entering’ in Ypsilanti, Michigan. Approach: Two measures relevant to environmental criminology were assessed: accessibility and surveillability. Findings: The findings indicate associations between incidents of crime and measures of visual accessibility. However, the level of homeownership was found to interact with the predictive models, suggesting the possible effect of ‘guardianship’. The geometrical shape of the isovist may also indicate where along a particular route, a crime is more likely to be committed. Originality: The results have the potential to assist law enforcement in identifying ‘hotspots’, and city planners in understanding the implications of urban design on crime.

Keywords

• isovists
• surveillance
• crime
• hotspots
• space syntax
• visibility graph analysis