The work previously described here can now be applied to isolate 360 degree isovists in contiguous space. Doing so provides four distinct spatial classes of isovist. Below we use the Soane Museum to outline these types.

‘Accessible’ space: when all walls used to define isovists are considered as solid and impermeable to vision, the isovists describe only that space which is directly accessible and can be walked into. This allows us to examine complex networks of circulation in an architectural plan.

‘Visible’ space (shown in cyan above): these isovists describe vision through a barrier that impedes direct access of space. Typically this can be used to examine complex networks of view in an architectural plan; accounting for vistas that lie beyond windows, balustrades or pools of water.

When we include isovists created as a result of reflective surfaces, they describe a further pair of spatial classifications. Firstly, ‘reflected’ space (shown in red above) can be defined as the existing space which is observed via a mirror. Secondly, ‘spectral’ space (shown in yellow above) can be defined as space which does not really exist, but which appears to exist ‘beyond’ the mirror surface. Together these two isovist sets can account for networks of materiality and reflection and their use in the creation of particular architectural spatialities.

These four classes of isovist can be combined with our approach to spatial field generation (described here). Doing so provides a methodology for quantitatively mapping and diagramming complex architectural configurations, based on the calculation and overlap of multiple layers of differing isovists. Initial taxonomies of the results of such analysis have been compiled for the Soane Museum (here) and the Barcelona Pavilion (here).