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1.
Abstract

A great deal of recent work in computer science applies itself to temporal database design. Designers of geographical information systems (GIS) can build on this work to create a temporal GIS capability to trace geographical change and understand geographical processes. This paper reviews temporal research in information processing, contrasts various proposed temporal database designs and summarizes the problems of adapting it to GIS requirements.  相似文献   

2.
Abstract

An intelligent expert system shell for the development of knowledge-based geographical information systems (GIS) is examined in this two-part article. Basic concepts and the overall architecture of the shell are discussed in the present part. Fuzzy logic and expert systems technology are demonstrated to be appropriate methods for approximating human reasoning and enhancing the level of intelligence in GIS. The shell can be employed as an effective and efficient tool for developing knowledge-based GIS.  相似文献   

3.
Abstract

Local government is one of the most important groups of users of geographical information systems (GIS). The significant interest amongst users and the varied demands to be made of GIS have stimulated discussion in many countries. This article presents some of the findings of a research project which is currently exploring the impact of GIS on British local government. The discussion examines the results of a comprehensive survey of all 514 local authorities in Great Britain. These findings provide an overview of GIS adoption in relation to type of local authority and geographical location. Particular attention is focused on the type of systems which have been adopted, the take-up of GIS over time, the software and hardware being utilized and the perceived benefits and problems associated with GIS. The results demonstrate that take-up has been most pronounced in the larger authorities, particularly in the southern part of Great Britain, with the most popular combination of equipment being Arc/Info software and workstations. For those authorities presently implementing a GIS, the technology is expected to improve existing capabilities for information processing rather than enhance decision-making or help achieve savings. In seeking these benefits authorities are encountering considerable problems which include basic technical difficulties in getting the equipment to work, data-related issues surrounding the collection, standardization and maintenance of geographical information, and profound organizational considerations associated with the introduction of information technology into complex environments. There is an urgent need for in-depth case studies which evaluate the experiences of users in relation to the vital process of implementation.  相似文献   

4.
Abstract

Abstract Chinese governments have long paid a great deal of attention to the collection of geodata, and existing sources have been further enhanced by technological advances, notably in remote sensing. Progress has also been made with automated cartography. An expert working group has been examining GIS and it is recognized that a system combining both national and regional components is most appropriate for China. Three basic functions are envisaged for such GIS: comprehensive regional analysis, prediction of change and the sharing of data. Such systems must serve the needs of users and, in order to demonstrate potential applications, regional experiments are being undertaken, including examples of urban information systems, river basin information systems and specialized systems (e.g. for tourist and forest resources). In the next few years, the emphasis will be on research and on technological preparation for the adoption of GIS, including the use of an experimental set of geographical grid cells. Chinese scholars are also involved in international collaboration in the study of global problems and propose a cooperative programme for a global geographical information system.  相似文献   

5.
Abstract

Research on time and data models for Geographical Information Systems (GIS) has focused mainly in the representation of temporal geographical entities and implementation of temporal databases. Many temporal GIS database structures have been proposed but most of them just provide principles, not the recipe for the design. Owing to the manipulation of the large quantity of geographical information and the slow response time, few implementations exist. This paper presents a relational method of storing and retrieving spatial and temporal topologies. Two-level state topologies are proposed: a state topology for a set of geographical entities and a state topology for a single geographical entity.

From a temporal perspective, these two-level state topologies may also be viewed as two-level time topologies: a time topology for all geographical entities in a GIS database and a time topology for a single geographical entity. Based on these state and time topologies, a detailed storage approach for historical geographical information is provided.  相似文献   

6.
Abstract

The planning and establishment of a geographical information system (GIS) relates to its context and intended use. GIS are a specialized type of information system, typically dealing with spatial data. This paper explores the environment of an envisaged GIS; the information utilization system and the wider object system. The planning and design of a GIS go beyond technical issues; they also have to take behavioural and organizational aspects of the utilization of information into account and contribute to a process of organizational development The paper is in two parts. The first (§ 2) explores salient aspects in the planning and design process, the second ( § 3) suggests some guidance in this task. The suggested approach of strategic choice in planning and establishing a GIS is designed to cope with the prevailing uncertainties in this planning process. It distinguishes between those decisions which have to be taken at once and choices which may be left open for the future.  相似文献   

7.
Abstract

Appropriate technology (AT) has become an integral part of the programmes for decentralized regional development in the Third World. ‘Appropriate’ techniques are usually low in capital costs; they can be maintained without a high level of expertise; and they do not involve patents, expensive copyrights and royalties. By these criteria a commercial geographical information system (GIS) is not an appropriate technology to be used in decentralized development However, the use of local renewable resources involves the adoption of end-use analysis for matching end-uses to specific sources so as to minimize the consumption of material and energy (i.e., minimize entropy). This matching requires much information which leads to what may be called the 'information-entropy trade-off; minimization of entropy requires an inverse increase in information. In this respect computers and GIS have an important contribution to make to decentralized regional planning. Drawing on a case study in Sri Lanka, this paper presents some ideas on how to incorporate GIS into local-level planning information systems.  相似文献   

8.
Abstract

The Institute of Terrestrial Ecology (ITE) Digital Cartographic Service provides a range of services to the scientists of ITE (and others) including various techniques within the field of geographical information systems (GIS). This paper discusses work of this type as it is applied to specific ITE projects. The emphasis is very much on GIS applications to ‘real ecological science’ such as the ‘acid water’ problem and the change of forest areas into heathland. Some comments are made on fundamental GIS techniques, their use and limitations. At ITE, GIS applications are growing out of an existing use of digital mapping and remote sensing technologies; they have not purchased a GIS system ‘off the shelf.’  相似文献   

9.
Abstract

A neglected aspect of facility location problems is the geometric representation of the facilities sited and clients served. Point objects represent these entities in most facility location problems. This can cause solution error and limit the range of potential solutions. The increasing capabilities of geographical information systems (GIS) to represent, store and manipulate spatial entities provides a substantial but unrealized potential for more sophisticated geometric representation in facility location problems. This paper provides a framework for realizing this potential. Specifically, this paper: (i) synthesizes existing formulations; (ii) develops a unified mathematical framework; (iii) identifies feasible computational strategies that can be implemented within a GIS framework, and; (iv) discusses potential GIS-based solution algorithms.  相似文献   

10.

Cartographic visualisation tools aid exploration, but they are designed for, and used exclusively by, experts. A democratised visualisation tool will include second-generation users, and these non-specialists might also want to use the available computer technology to visualise their geographical data. In this paper, we argue that democratised GIS should have a functionality similar to visualisation tools and we forward our opinion on how these can be developed in order to do so. Our emphasis is on interactivity regarding representation methods and on elaborating principles for implementing map type selection in interfaces for democratised GISs.  相似文献   

11.
Abstract

A geographical information system (GIS) is used as an important tool in increasing the efficiency of planning and decision making, leading to a more equitable distribution of wealth and welfare. However, scarce financial and technical resources in developing countries require that a flexible approach must be adopted when developing a GIS. In Saudi Arabia, where the planning and funding decisions relating to municipal services are taken centrally by the Ministry of Municipal and Rural Affairs (MOMRA) and implemented through its regional and local branches and municipalities, the setting up of a GIS is considered essential. An incremental method was chosen for establishing a GIS in the municipal sector by means of several phases. This paper discusses the main steps and strategies for each phase, the level of achievement since the implementation of the Municipal Information System (MIS) in 1983, and current views of the system's future. It was concluded that an incremental implementation of a MIS seems to be a practical and effective solution. However, weaknesses and problems, such as the long period of implementation and a lack of co-ordination between different agencies and offices, must be resolved to ensure ultimate success of such an approach.  相似文献   

12.
Abstract

With the rapid growth in the use of geographical information systems (GIS) has come an acute shortage of skills. Although traditional techniques of education and training based on courses at various levels are being widely exploited, there is special potential in GIS for the use of demonstrators and tutors. Such computer aided learning (CAL) tools offer an effective way of putting across the graphical concepts which are vital to GIS as well as offering an attractive form of self-paced study. This paper discusses the contribution of CAL tools to GIS education and offers a short history of the techniques. A case study of the development of the Geographical Information Systems Tutor (GISTutor) is also used to illustrate the educational and technical issues behind the creation and use of such a tool.  相似文献   

13.
Abstract

Remotely-sensed data constitute a major potential source of input to geographical information systems (GIS)However, these data often have a relatively poor classification accuracy compared with that of the cartographic data from maps with which they may be combined in the course of GIS analysis. The possibility exists of using data sets (in the form of digital maps) resident within a GIS in order to improve this accuracy, before the classified image is incorporated into the GIS. Results are discussed from a British Alvey Information Technology project to develop a system for the knowledge-based segmentation and classification of remotely-sensed terrain images, in which the knowledge contained in digital map  相似文献   

14.
Currently used methods for representing geographical information are inadequate because they do not tolerate imprecision. This leads to information loss and inaccuracy in analysis. Such expressive inadequacy is largely due to the underlying membership concept of classical set theory. To improve information processing in GIS research and application, an alternative membership concept is required. In this paper, we explore the inadequacy imposed upon geographical information representation by classical set theory and address the problems of information loss. A fuzzy relational data model is defined which is more representative for geographical information. A GIS database for agricultural land resource management is created by using the data model and a new technique for assessing land suitability is developed. The fuzzy representation largely facilitates data analysis in this GIS. The methods are tested with data from North Java, Indonesia using a vector-based GIS software package, Arc Info, and the analysis results are presented.  相似文献   

15.
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16.
Abstract

During the 1980s techniques for analysis of geographical patterns have been refined to the point that they may be applied to data from many fields. Quantitative spatial analysis and existing functions available in geographical information systems (GIS) enable computerized implementations of these spatial analysis methods. This paper describes the application of quantitative spatial analysis and GIS functions to analysis of language data, using the extensive files of the Linguistic Atlas of the Middle and South Atlantic States (LAMSAS). A brief review of recent development of using quantitative and statistical methods for analysing linguistic data is also included.  相似文献   

17.
Abstract

A vector-based geographical information system (GIS) is used to generate a variably-sized triangular element finite-element mesh from mappable features. Important digitally-mapped features are automatically linked to nodes in the finite-element model, ensuring an efficient, virtually error-free alternative to the tedious process of mesh design and data-input preparation by other methods. The procedure permits the user to work interactively with graphically-displayed hydrologic information about the study area allowing different mesh sizes to be used as needed, based on hydrologic complexity. The mesh-generaiion programs are stand-alone macros within the GIS that set up the basic data defining a finite-element mesh for many different finite-element model programs.  相似文献   

18.
Abstract

A geographical information system (GIS) has proved to be a valuable tool in the Direct/Delayed Response Project—a comprehensive examination of the future, long-term chemical response of surface waters to acidic deposition. The role of the GIS within the project includes aggregation, analysis and display of various forms, scales and projections of environmental data related to acidic deposition. The GIS is particularly valuable for effectively communicating key scientific findings and results of regional, national and international importance to a diverse audience.  相似文献   

19.
Abstract

Although biological diversity has emerged in the 1980s as a major scientific and political issue, efforts at scientific assessment have been hampered by the lack of cohesive sets of data. We describe, in concept, a comprehensive national diversity information system, using geographical information system (GIS) techniques to organize existing data and improve spatial aspects of the assessment. One potential GIS analysis, to identify gaps in the network of nature reserves for California, is discussed in greater detail. By employing an information systems approach, available data can be used more effectively and better management strategies can be formulated.  相似文献   

20.
Abstract

Recent developments in geographical information systems have drawn upon concepts of fuzzy set theory and multi-criteria methodology. In this paper we argue that there is a method, Saaty’s Analytic Hierarchy Process (AHP), that is compatible with both these research directions. The contributions of the AHP are highlighted in the light of recent developments in GIS, with particular attention to the concept of fuzzy set theory. An example of a GIS application is provided to show how the AHP can deal operationally with fuzziness, factor diversity and complexity in problems of land evaluation involving the location of a public facility.  相似文献   

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