Spatial Analysis of Building Indoor Environments Using 3D Isovist

Mahshid Jalalianhosseini PhD Student in Architecture, University of Wisconsin-Milwaukee
Kyle Talbott Associate Professor, University of Wisconsin-Milwaukee
Brian Schermer Associate Professor, University of Wisconsin-Milwaukee
Mark Samuel Richter Undergraduate Student in Architecture, University of Wisconsin-Milwaukee

Isovist is an objective graphical means for comprehensive mapping of environments which represents the set of all points visible from a given point in space. In other words, the isovist can be thought of as the volume of space illuminated by a point source of light. Research in environment and behavior suggests that isovist analysis captures perceptually and behaviorally relevant properties of space and can relate to issues like wayfinding and users’ experience of buildings.

Current isovist methods mainly accept a planar representation of an environment such as a floor plan drawing of a building and they produce a 2-dimensional analysis. While helpful, this has some shortcomings as some architectural characteristics are not captured by two-dimensional analysis. These include vertical characteristics of atrium spaces and areas in the building with staggered floor and ceiling heights. Therefore, for a comprehensive evaluation of environment we need to study a 3D isovist which can provide a volumetric measure of visual experience.

Because of some computational challenges, tools for calculating 3D isovists are rare. The current study proposes a method that departs from planar restrictions by using the parametric modeling capabilities in Rhino’s Grasshopper plugin. For this purpose, a definition has been developed in Grasshopper and used to derive measures for 3D isovists using a hybrid method of ray-casting and voxel-packing. This definition can be used to compare spatial properties of different areas in a model of a building or study the relationship between two or more spaces.

The study uses the developed method for analysis of hypothetical and real environments. The student union building at University of Wisconsin-Milwaukee has been selected and analyzed. This study therefore contributes to analysis of architectural environments relative to human perception and cognition by presenting a robust method for analysis of 3D isovist and measures derived from it.

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