A Multimedia City Model for Environmental Impact Assessment and Public Consultation Kevin McCartney, Ashraf Ismail and Philip Rhodes School of Architecture University of Portsmouth King Henry Building King Henry I Street Portsmouth PO1 2DY ABSTRACT Experiments with different techniques for creating multimedia models of city zones are being carried out in the School of Architecture in University of Portsmouth. This work is part of a cooperative project with the Department of Economics, the New Media Centre, and the Photogrammetry Unit in the Department of Geography, aimed al developing a prototype multimedia model of a sizable part of the City of Portsmouth. The model is designed to facilitate user interaction, and will be tested to evaluate its potential contribution to the process of public consultation, and in facilitating communication between different specialists engaged in the production of environmental impact statements required by the EC Environmental Impact Directive (85/337). To date, work has focused on two areas: assessing the viability of different techniques for generating the three-dimensional model, and creating a multimedia framework for both storing and retrieving information related to the environmental impact of development proposals. Introduction A considerable amount of investigative work has been undertaken in Portsmouth School of Architecture, which demonstrates the very significant difficulties involved in any attempt to disseminate information in the architectural profession. "Well-established scientific, technical and social knowledge about the built environment is mostly unexploited by architects" (Newland, Powell and Creed, 1987). This rather gloomy observation led to work on improving the accessibility of information through improved communication techniques, and to attempts to understand the underlying problem of the attitudes of professionals to information access based on learning theory. The problem is probably not confined to the architectural profession. The United Nations made the following comment regarding environmental impact assessments: "A vital feature... is the information that is presented... Important also are the techniques of communication" (Clark & Bisset, 1981). The potential for improved communication offered by software systems which ecaade 1993 - PDF-Proceedings (conversion 2000) 6-25
combine visualisation of the city, with analytical data about the city has been highlighted by Dupagne (1991). The Portsmouth Multimedia City Model is an attempt to develop these ideas. A Tale of Two Cities The package under development consists of two discrete but interactive systems. The first part, the 3D City, is a computer generated geometrical visualisation of the city fabric. The second part, the information city, includes a collection of textual, visual and audio information pertaining to the city. Both the 3D City, and the Information City are presented on the same computer screen. In this way it is hoped to make visible, the hidden city; to begin to expose the framework of information which underlies all human endeavours and systems. Many of the required model creation tasks have already been explored by earlier workers in the field. Grant (1991) reports on work in ABACUS, in the University of Strathclyde, where a model of the city centre of Glasgow was created in 1986. He also describes more recent developments to the model and describes "a long-term aim to achieve a system... where the buildings ihemselvesform the icons through which queries can be made... This ineans that as users 'walk' down streets they can interrogate what they see". Our team determined to explore the possibility of achieving such an aim using off-the-shelf software and the ubiquitous MS-DOS, Intel 486 desktop computer, coupled with a fast graphics processor (SPEA Graphiti-Hilite). The 3D City Creation Another significant development in the UK has been the work of Dr. Alan Day at the University of Bath, who has led a team which has adopted the industry standard package AutoCAD, from Autodesk inc. to create very detailed representations of large numbers of buildings throughout the city. The adoption of widely used CAD software, or at least widely adopted drawing exchange format in the software used to create city models, has the clear benefit of facilitating the incorporation of new building proposals into the model, and the continuous updating of the model. The importance of regular updating has been stressed by city planners with whom we have discussed our proposals. They consider six monthly updates to be a minimum requirement, if the system is to be utilised as an aid to the planning process. An initial geometric model of a part of Portsmouth occupied by the University's western campus has been created within the Autodesk AutoCAD environment. This was created by "tracing" a digital graphic representation produced using stereographic aerial photography in a digital analytical plotter in the Photograminetry Unit of our Department of Geography. The need to "trace" the photogrammetric output was an unfortunate inefficiency in this first stage caused by a lack of ecaade 1993 - PDF-Proceedings (conversion 2000) 6-26
Figure 1. Glimpses from the 3D City. original files. It is hoped that simple block models representing roof plans and building heights will be produced in a form that can be imported directly into AutoCAD, in our next use of this technique, which will be to extend the coverage of the model beyond the present 2 km2. Models created in this way can be enhanced using rendering packages such as Autodesk 3DStudio, and the skills to expand such a model are available in the built environment professions. There are however difficulties related to speed of display when the model incorporates large numbers of buildings, or objects. This therefore would compromise one of primary objectives of achieving a high degree of user interaction with, or via, the three-dimensional model. The limitations associated with manipulating three-dimensional models in AutoCAD, in real time, led us to consider two alternatives for the display of the model. Experience had already been gained in creating three-dimensional animations and storing on a WORM laser disk system (Rhodes, 1993). Single frames of animation could be generated in AutoCAD, or in 3DStudio, dumped on to the laser disk, and retrieved in a random access format, controlled by standard multimedia software. This would enable high degrees of photorealism to be achieved in the display of animation, but it would entail the limitation of 'movement' through the city to routes pre-determined by the creators of the model. This was also considered to compromise the project objectives. The Interactive 3D City An alternative medium for the model generation has therefore been explored. This involves the creation of a model in a 'desktop virtual reality' system, Superscape from Dimensions Ltd. was selected. This offers the benefits of very fast real-time interaction with a three-dimensional model. ecaade 1993 - PDF-Proceedings (conversion 2000) 6-27
It does not match the precision and detail one might expect in a CAD model, but compensates in the realism of 'movement' through models, and through the potential to control interaction with objects which are displayed. Superscape offers techniques for integrating modelling rules to determine the behaviour of objects. For example, cars moving through the city model could be controlled by a System user, but limited to moving only on roads. This facility may be of particular value in illustrating environmental phenomena of interest in an environmental impact study. Wind/building interactions, for example, could be represented by animated icons, and explored from different perspectives selected by the model user. The analysis of such phenomena would normally be analyzed in wind tunnels or in a computational fluid dynamics CFD package, and the significant results then translated into the Superscape system. It is however not fanciful to project the development of translator/filters which would enable direct connections to be established between the three dimensional visual model, and a CFD model. Another feature of the Superscape software which facilitates its use in presenting large models, is its ability to turn architectural detail on, or off, according to the 'distance' of the viewer from buildings. This economises on the size of the model in the display memory at any specific time, facilitating rapid manipulation of the model. Multimedia and the Information City Information is presented using a variety of multimedia techniques; video, text, animation and audio commentary. Multimedia techniques appear particularly appropriate when addressing environmental impact statements. Their ability to juxtapose many different descriptions of the same phenomena, or of different phenomena at the same location, provide the basis for a deeper understanding of the interdependent nature of environmental phenomena. Furthermore, multimedia is particularly well suited to presenting qualitative, as well as quantitative information. Therefore opinions of the local residents, and professionals can be included, with the intention of providing a more holistic impression of the city. Accessing the Inforrnation City Information is indexed in two ways; firstly in terms of the data type, hence there will be information regarding specific environmental phenomena, and secondly information about specific locations, or objects, within the city. Hence information can be accessed both by searching under menus represented by icons on the multimedia interface to the model, and by pointing at locations in the three-dimensional geometrical representation of the city through which the user 'moves'. This extends into an additional dimension the concept of two-ditnensional spatial organisation of data, which has become familiar in the ubiquitous desktop analogy of contemporary WIMP operating environments. The information is selected by the user, and then presented to them, through a device which they 'carry' on their journey through the 3D City. The device, referred to as the 'Personal Information Retrieval Node' (P.I.R.N.) is designed to allow the user to ecaade 1993 - PDF-Proceedings (conversion 2000) 6-28
move rapidly between a three dimensional view of the city to the information pertaining to that part of the city. Each user of the package, has a personal node, this not only reinforces the idea that the model and the information can be explored in terms of a user's own interests, requirements; but also allows the user to make notes. Figure 2. Personal Information Retrieval Node (P.I.R.N.), allowing access to the 7nformation City', whilst within the '3D City'. Conclusions At this stage, a suitable interface has been designed, the required interconnections have been specified, and a prototype interactive 3D model of a small part of the city of Portsmouth has been produced. Future work will include the expansion of the model, experiments on the relationship between levels of graphic detail and location recognition and way-finding behaviour in system users, and the development of appropriate formats for representing invisible phenomena such as wind movement within the 3D city. References Clark, B. & Bisset, R. (1981) Methods of Environmental Impact Analysis in the United Kingdom: Current Practice and Future Prospects, in Proc. of Environmental Impact Assessment Seminar, United Nations Economics Commission for Europe, Villach, Austria, September. 1989 Pergamon Press, New York,. Dupagne, A. (1991), A Computer Package to Facilitate Inhabitants' Participation in Urban Renewal, Environment &Planning B. Planning & Design, Vol. 18(1), p119-134 Grant, M. (1991) ISSUE: Integrated Software Systems for the Urban Environment, Environment & Planning B, Planning & Design, Vol. 18(1), p 33-38. Newland, P. Powell, J. & Creed, C. (1987), Understanding Architectural Designers' Selective Information Handling, Design Studies, Vol. 8, No. 1, January 1987, p 2-16. Rhodes, P. (1993) Narrative Structure and ist Role in the Transfer of Architectural lnformation Through Video and Interactive Video, unpublished PhD thesis, School of Architecture, University of Portsmouth. ecaade 1993 - PDF-Proceedings (conversion 2000) 6-29
Order a complete set of ecaade Proceedings (1983-2000) on CD-Rom! Further information: http://www.ecaade.org