Three-dimensional representation of urban built form in a GIS

The Smallworld GIS has been customised to create a means of representing th e three-dimensional forms of buildings. To do this, buildings are broken do wn into floor polygons: among whose attributes are floor lever and storey h eight. Data for nondomestic buildings at 3350 addresses in four English tow ns have been entered into Smallworld, and measurements made of floor areas, roof areas, and exposed wall areas. Floor polygons may be reaggregated int o premises, built forms, or by other attributes. Several applications in en ergy analysis and urban planning are described.