Environment and Planning B: Urban Analytics and City Science

The measurement of spatial pattern is often undertaken using one of a number of single-number indices, such as the Gini coefficient, which may not illuminate certain aspects of the pattern involved—especially the degree to which the members of the reference group are spatially concentrated. We suggest an alternative approach based on a concentration profile which shows the degree to which a group is spatially concentrated according to a range of thresholds. This is illustrated with data on male unemployment in England and Wales in 1991, which also shows the importance of spatial scale to the study of concentrations and, potentially, to the formulation of spatially focused public policies.

Retailers use analogues (similar stores) routinely in the process of site assessment, either as a basic method of sales forecasting in its own right, or as a check on more complex quantitative models. In earlier stages of our research, we identified intuitive or qualitative causal knowledge structures derived from cognitive mapping interviews with UK retail directors to classify new sites according to their degree of likeness on these same attributes. Here, we focus on how the analogues identified by our qualitative system can be visualised effectively for use in location analysis. We discuss the role of analogy in retail location decisionmaking and the advantages and disadvantages of different methods of visualisation. We evaluate the visual aspects of the system developed in the course of our research with reference to users' qualitative responses. The central issue appears to be the value users place on the system being able to summarise analogues simply on key dimensions at a general level, as well as its ability to ‘drill down’ into the detail so that analogue representativeness can be established.

This paper reports on a primary metric tool developed in a collaboration between an architecture researcher and a computer science researcher. The development of this tool emerged from the concept that the spatial openness (SO)—the volume of free space measured from all possible observation points—is an important quality indicator of alternative spatial configurations within given constraints; this concept is based on the idea that the geometry and morphology of the built-up environment influence perception. Previous work showed that comparative SO measurements in alternative spatial configurations are correlated with the comparative perceived density, and in particular that a higher value of SO indicates a lower perceived density. We present a feasible 3D computational method for measuring SO and demonstrate its potential use in the design process. The SO metric is a step towards the development of quantitative comparative evaluation of building shapes and spatial configurations related to the 3D observation of open space.

This paper focuses the novel GIS-related aspects of a prototype planning support system for urban planners and energy advisers. The system design combines commercial database and GIS packages to provide a flexible means of predicting the solar energy potential and energy consumption of dwellings. By incorporating customised tools designed to derive useful data directly from digital maps and aerial photographs, it addresses the significant problem of data collection for urban-scale energy modelling. In conjunction with data generated by a new dynamic default data system, the map-derived data provide the necessary input for an embedded domestic energy model and a solar energy calculation engine. In this way, robust estimates can be obtained, at almost arbitrary scales of resolution, of the potential for solar energy to replace delivered domestic energy and to mitigate emissions of carbon dioxide.

Activity-based accessibility measures, describing the level of access to spatially distributed activities, are not put to the same use in land use and/or transport policy evaluations as are infrastructure-based accessibility measures, which describe congestion levels or the average speed on the motorway network. In this paper we attempt to improve the current evaluation practice by the application of potential, activity-based, accessibility measures for the analysis of job accessibility, using existing traditional land-use and transport data and/or models. We try to improve the interpretability of the results by estimating the separate influence of land-use changes, infrastructure projects, and congestion on the development of job accessibility. A case study of the Netherlands shows the importance of incorporating job competition and the match between educational and job levels in the analysis of job accessibility.

The authors examine the relevance of public participation geographic information systems (PPGISs) to housing-estate management in Singapore. Formal interviews were conducted with five key informants to collect data. A mock-up PPGIS was developed and evaluated. Informal interviews with property managers and secondary data also contributed to the discussions. Findings suggest that the current level of information technology applications and the mandate to build a ‘People's Town’ in Singapore's public housing estate have laid a solid base for introducing PPGIS to housing-estate management. The existing channels of public participation in town council management also pointed to a collective form, based on the Residents' Committees, for accessing and using the PPGIS. It is hoped that this study contributes to PPGIS research by extending explorations to a new cultural context and to a new application area.

This paper introduces procedures involving the recursive construction of Voronoi diagrams and Delaunay tessellations. In such constructions, Voronoi and Delaunay concepts are used to tessellate an object space with respect to a given set of generators and then the construction is repeated every time with a new generator set, which comprises members selected from the previous generator set plus features of the current tessellation. Such constructions are shown to provide an integrating conceptual framework for a number of disparate procedures, as well as extending the existing functionality of the basic Voronoi and Delaunay procedures to variable spatial resolutions. Further, because they are shown to be fractal in nature, it is suggested that this characteristic can be exploited in the development of new strategies for spatial modelling.

The concept of emergence has its roots in 19th-century philosophy. Today it is central to many computational systems which retain the hallmarks of emergence laid out much earlier. The role of emergence in creative design and its unique embodiment in shape grammars have been emphasized by March, Stiny, and others. Shape grammars generate emergent shapes—shapes not predefined in a grammar. Emergent shapes are not only the output of a shape grammar computation; they can be the input for further computation. The history of emergence and its characterization in shape grammars are discussed here. Different sorts of shape emergence in grammars are then distinguished: anticipated, possible, and unanticipated. Unanticipated emergent shapes are shapes not premeditated by the author or user of a grammar. Generally, unanticipated shapes require on-the-spot definitions of rules to compute with them. However, for some interesting design problems, it is possible to know in advance what to do with unanticipated shapes, and to predefine rules accordingly. Special rules for computing with unanticipated shapes are proposed here. These rules allow for processes that have previously been handled extragrammatically—outside of grammars—to be handled within grammars. Examples of applications of these rules within a single grammar and across parallel grammars are given.