Using isovists to analyse architecture: methodological considerations and new approaches

In the late 1970s architectural researchers developed the isovist, a new approach to analysing the geometric properties of spatial visibility. An isovist is a representation of the space that is visible from a point within a building. Today isovists are part of the broader field of research known as visibility analysis. Visibility analysis applies mathematics to architectural and urban space to investigate the relationship between form, vision and human behaviour. While the concept of an isovist is widely accepted, there are multiple approaches to constructing isovists. Researchers have also developed a wide range of measures from isovist analysis, many of which claim to offer unique insights into architectural space. Using a hypothetical building plan as an example, this paper provides a consistent and critically framed demonstration of architectural analysis using isovists, isovist view fields and global visibility properties. These worked examples include an explanation of two construction methods for isovists along with mathematical and diagrammatic approaches for producing local and global visibility measures. Importantly, the paper demonstrates an original use of the isovist view field to support the manual calculation of global visibility properties while avoiding the construction of a full visibility graph. In presenting this detailed and critical review, the paper also identifies a number of factors requiring further study and considers issues of accuracy, consistency and repeatability pertaining to the method.