In this paper a semiautomated morphological classification of urban space is addressed systematically by sorting through the volumetric shapes of public spaces represented as 3-dimensional convex and solid voids. The motivation of this approach comes from a frequent criticism of space syntax methods for lacking information on how buildings and terrain morphology influence the perception and use of public spaces in general and streets in particular. To solve this problem information on how façades relate with streets and especially information about the facades’ height should be considered essential to produce a richer and more accurate morphological analysis of street canyons and other open spaces. Parametric modelling of convex voids broadens the hitherto known concept of two-dimensional convex spaces considering surrounding facades’ height and topography as important inputs for volumetric representation of urban space. The method explores the analytic potentials of ‘convex voids’ and ‘solid voids’ in describing characteristics of open public spaces such as containment, openness, enclosure, and perceived enclosure, and using these metrics to analyse and classify urban open spaces.