Environment and Planning B: Urban Analytics and City Science

The Spanish Ministry of Finance is carrying out, at the national level, a computerised verification of cadastral data with two fundamental objectives: to set up a file of land parcels in order to ease the task of making future revisions both to planning and value changes; and to establish a definitive method for administering urban land taxes. In this paper a project is described whose purpose is to digitise cartographic parcel information and integrate it with alphanumeric information in a standard computer document. The project is being carried out in the Municipality of Teror on the Gran Canaria island.

The process of development is described of a planimetric model whose purpose is twofold: the verification of total areas and standards in the Master Plan for Milan, and the creation of an urban land register for the city. Comparisons of the results of previous appraisals have demonstrated the necessity of moving from a purely graphical form of management (either manual or computerised) to methods based on planar maps, reinforced by the use of vectorisation techniques and automatic recognition of polygons. The paper is divided into three parts. In the first part the management problems arising from the process of urban change in Milan are outlined. In the second the concepts used to define the structure of data relating to the city, and to preserve the internal consistency of those data are illustrated. In the third part the algorithms used and the stages of work are demonstrated, from scanning of hand-drawn plans through to automatic construction and checking of maps.

The TRAPU system developed by the Institut Géographique National is a computer tool for the digitising and modelling of three-dimensional urban forms using photogrammetric techniques. The data structures employed allow the creation of convex polyhedra, laminae and lines in space. Topography of the ground surface may be represented by triangulated surfaces. Perspective and orthographic views can be created. Data can be exchanged with other CAD systems. Applications of the system so far have been mainly for visualising architectural projects in context, and for studying the impact of new roads and large urban developments.

The paper describes the project Verso Genova Medievale, whose aim is the reconstruction by means of computer graphic techniques of a portion of the medieval centre of Genoa as it appeared in the late 15th century. The visual presentation will be supported by an interactive videodisk. The work has brought together fundamental historical and architectural research with advanced computer rendering techniques, to simulate a walk through the centre of the medieval city with a high degree of interaction. The project has revealed some limitations in present computer tools for these purposes. Suggestions are made as to where further developments are needed.

A current project at ABACUS is to develop a specification and produce a partial implementation of an interactive software system through which information on the urban environment can be compiled, maintained, and accessed. The heart of this prototype is a geometrical model of the terrain, buildings, and transport networks covering an area of some 20 km² in and around the city centre of Glasgow. A database of upwards of ten thousand buildings is now in existence, from basic block outlines to fully detailed architectural models. The current research is intended to enhance the data set by providing a series of software bridges between the geometry model and extant alphanumeric databases. Advances in computer hardware and in information technology software offer the prospect of an integrated system relating to the urban environment—a database of databases—which would be accessible to all those who plan, manage, work in, live in, or simply visit the city.

In this paper examples are given of how modern information technology may have an impact on the way we build and use computerised models for different applications. The KBS-MEDIA (knowledge-based systems-media) group of projects is described. These projects are aimed at integrating advanced software techniques (knowledge-based systems, HyperCard from Apple Computer, etc) with new distribution and storage media. The ‘hyperdocuments’ which are created possess powerful man-machine interface and dynamic model-building properties. The system described forms a demonstration environment used in different applications to capture, test, and communicate ideas, so allowing fast prototyping. New tools for building and using ‘hypermedia’ systems have been defined, created, and tested. These tools are adapted to the needs of the people intended to use them, by means of ‘friendly’ interfaces. Some comments are made on the ideas behind the project, as well as on how the KBS-MEDIA environment is used in the ‘City Advisor’ application.

A specific approach is described to the elaboration of a new-generation three-dimensional image-synthesis system built around a language taken as the main communication medium between the different modules of the system. The outlines of the subject are deliberately limited to the data-acquisition and object-construction aspects. Theoretical and methodological deductions are drawn from the possibility of converting different data used in the various modules. These are illustrated with examples of visualisation of urban scenes. A common language medium is proposed to support the ‘intelligent’ behaviour of the system, which starts to work once a critical threshold is reached: first, through a learning module based on a user-system dialogue; then through the further development of the system in a progressive self-learning mode.

The author describes the development of a computer tool for urban design and the study of urban morphology: the Town Simulator. The incoherence and lack of cohesion which have characterised much recent urban development show the urgent need for such a tool. Several factors are identified as the source of our ‘urban misunderstanding’: the complexity of the planning problems involved; certain ideas in the philosophy of modernism in architecture; the multiplicity and discordant character of our democratic society. Many ingredients of urban character are listed, which the Town Simulator must take into account, including environmental factors, the nature of streets and open spaces, the shape and size of building parcels and their patterns of occupation and use, architectural morphologies, and building regulations. The Town Simulator is being built using a flexible rule-based approach to the construction of architectural and urban objects. It is argued that three-dimensional modelling by computer offers a means for overcoming some of the urban design problems identified in the paper.

A project developed at the GAMSAU laboratory, Marseille-Luminy School of Architecture, aimed at the creation of a prototype system for urban simulation using artificial intelligence and computer graphics techniques is described. The project is developed in Smalltalk-80. The prototype presented gives an indication of what is envisaged for the complete system, which will comprise a database of urban knowledge and a computer graphics visualisation module.

During the last six years the authors have been working in the Centre for Configurational Studies on a series of research projects whose overall aim is to increase knowledge of the composition and morphology of the English building stock. Earlier work was devoted to domestic buildings—houses and apartments—whereas more recent research is concerned with nondomestic building types, focusing particularly on offices and shops. Two large surveys are described of domestic and nondomestic buildings made in Cambridge and Swindon, respectively. This empirical work has been accompanied by the development of a theoretical morphology or science of architectural form which attempts to explain why certain plans and built forms occur in practice and not others. It is only on the basis of such a theory, the authors argue, that any scientific generalisations can be built about the relationships of form to performance. A central feature of the approach to morphological classification taken here is the separation of shape or configurational properties from dimensional or metric properties.

The authors describe the application of computer techniques in a special example of technical management of the architectural and urban fabric. This relates to a restoration and rehabilitation programme being carried out in Marseille's old city quarters which will involve reconstruction of facades. The GAMSAU laboratory has chosen this example as a testing ground for the development and analysis of the requirements for a computerised data management system. The data to be collected will include descriptions of the current state of facades and details of their historical evolution complete with drawings, photographs, and colour palettes. The computer system will be based on a database management package, and will feature structured object description, multimedia data support, sharing and distribution of data among users, the integration of different applications software, handling of design alternatives, and keeping of progress records.

The author draws attention to certain problems encountered in the business of simulation of urban ambient environments. He aims, in the first place, to situate the whole problematic of the urban environment in relation to recent thinking on the subject of the design and administration of cities and urban projects. He then approaches the theoretical and methodological problems posed by a double characterisation of environment in terms of objective and subjective elements. Finally, drawing from CERMA's own experience, he lists a series of practical obstacles whose solution can surely provide a focus for the international cooperation in research which is strongly urged in this paper.