Requirements and principles for the implementation and construction of large-scale geographic information systems

Abstract

This paper provides a brief survey of the history, structure and functions of ‘traditional’ geographic information systems (GIS), and then suggests a set of requirements that large-scale GIS should satisfy, together with a set of principles for their satisfaction. These principles, which include the systematic application of techniques from several sub-fields of computer science to the design and implementation of GIS and the integration of techniques from computer vision and image processing into standard GIS technology, are discussed in some detail. In particular, the paper provides a detailed discussion of questions relating to appropriate data models, data structures and computational procedures for the efficient storage, retrieval and analysis of spatially-indexed data.     

Analysing telemetry data with a GIS-based vector structure

Abstract

This paper proposes a unique method for plotting field bearing locations, of the kind typically taken by wildlife biologists on free ranging species, directly on a computer-compatible habitat map. We show how to use a GIS data base to identify differential habitat use directly from the polygon formed by each set of bearings. A geometric algorithm is developed to interpret the bearings accurately. The technique avoids the most difficult errors associated with using point locations, namely those due to animal movement, and distance from receiver to transmitter, and is especially useful for habitat preference studies.     

Coordinating hazardous waste management activities using geographical information systems

Abstract

This paper describes a framework for the role of geographical information systems (GIS) in the monitoring and management of hazardous waste sites. Compilation of required information, incorporation of existing strategies for waste monitoring, analysis of these data in a GIS environment and the integration of computerized models for transport processes are discussed. Examples for the analysis of spatial data using techniques of cartographic overlay and the implementation of geo-statistical methods on monitoring data are provided from work in progress by the authors. These examples are set in the context of developing a fully integrated monitoring and management system utilizing GIS technology.     

Land cover classification by an artificial neural network with ancillary information

Abstract

Remote sensing is an important source of land cover data required by many GIS users. Land cover data are typically derived from remotely–sensed data through the application of a conventional statistical classification. Such classification techniques are not, however, always appropriate, particularly as they may make untenable assumptions about the data and their output is hard, comprising only the code of the most likely class of membership. Whilst some deviation from the assumptions may be tolerated and a fuzzy output may be derived, making more information on class membership properties available, alternative classification procedures are sometimes required. Artificial neural networks are an attractive alternative to the statistical classifiers and here one is used to derive a fuzzy classification output from a remotely–sensed data set that may be post–processed with ancillary data available in a GIS to increase the accuracy with which land cover may be mapped. With the aid ancillary information on soil type and prior knowledge of class occurrence the accuracy of an artificial neural network classification was increased by 29–93 to 77–37 per cent. An artificial neural network can therefore be used generate a fuzzy classification output that may be used with other data sets in a GIS, which may not have been available to the producer of the classification, to increase the accuracy with which land cover may be classified.     

Spatial analysis of linguistic data with GIS functions

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.     

An inductive modelling procedure based on Bayes' theorem for analysis of pattern in spatial data

Abstract

This paper describes an inductive modelling procedure integrated with a geographical information system for analysis of pattern within spatial data. The aim of the modelling procedure is to predict the distribution within one data set by combining a number of other data sets. Data set combination is carried out using Bayes’ theorem. Inputs to the theorem, in the form of conditional probabilities, are derived from an inductive learning process in which attributes of the data set to be modelled are compared with attributes of a variety of predictor data sets. This process is carried out on random subsets of the data to generate error bounds on inputs for analysis of error propagation associated with the use of Bayes’ theorem to combine data sets in the GIS. The statistical significance of model inputs is calculated as part of the inductive learning process. Use of the modelling procedure is illustrated through the analysis of the winter habitat relationships of red deer in Grampian Region, north-east Scotland. The distribution of red deer in Deer Management Group areas in Gordon and in Kincardine and Deeside Districts is used to develop a model which predicts the distribution throughout Grampian Region; this is tested against red deer distribution in Moray District. Habitat data sets used for constructing the model are accumulated frost and altitude, obtained from maps, and land cover, derived from satellite imagery. Errors resulting from the use of Bayes’ theorem to combine data sets within the GIS and introduced in generalizing output from 50 m pixel to 1 km grid squares resolution are analysed and presented in a series of maps. This analysis of error trains is an integral part of the implemented analytical procedure and provides support to the interpretation of the results of modelling. Potential applications of the modelling procedure are discussed.     

An information systems approach to the preservation of biological diversity

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.     

Mapping glacier velocities on Svalbard using ERS tandem DInSAR data

The results presented show how glacier velocities can be measured and calculated from Earth Resources Satellite (ERS) tandem interferometric synthetic aperture radar (InSAR) data by the use of geographical information systems (GIS) and non-interferometric software. A semi-automatic algorithm using existing and newly implemented modules in ESRI's GIS software Arc has been developed to unwrap existing height differentiated interferometric SAR (DInSAR) data. The algorithm is applied to a data set covering glaciers from the arctic archipelago Svalbard. Estimated DInSAR velocities are decomposed into the glacier surface flow direction using a digital elevation model (DEM). Velocity fields for the glaciers Isachsenfonna, Akademikerbreen and Nordbreen on Svalbard are presented.     

Constructing Interfaces between (and within) Geographical Information Systems

Abstract

An interface is a software package used, alone or in conjunction with other interfaces, to transfer data from one geographical information system to another, or between different representations within a single GIS. The aim in this paper is to extend the traditional view of an interface to include interfaces that use communication networks to move data between (and within) GIS. We suggest that, to exchange data across a network, the best solution may be to construct a set of communicating interfaces, each able to send data to, and receive data from, other communicating interfaces. We describe a working set of communicating interfaces that transfer data between a number of GIS data representations.     

Finite-element mesh generation from mappable features

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.     

Integrating multi-criteria evaluation with geographical information systems

Abstract

Geographical information systems (GIS) provide the decision-maker with a powerful set of tools for the manipulation and analysis of spatial information. The functionality of GIS is, however, limited to certain deterministic analyses in key application areas such as spatial search. The integration of multi-criteria evaluation (MCE) techniques with GIS is forwarded as providing the user with the means to evaluate various alternatives on the basis of multiple and conflicting criteria and objectives. An example application based on the search for suitable sites for the disposal of radioactive waste in the UK using the Arc/Info GIS is included. The potential use of a combined GIS-MCE approach in the development of spatial decision support systems is considered.     

Fundamental operations in computer-assisted map analysis

Abstract

Geographical information systems (GIS) provide capabilities for the mapping, management and analysis of cartographic information. Unlike most other disciplines, GIS technology was born from specialized applications. A comprehensive theory relating the various techniques used in these applications is only now emerging. By organizing the set of analytic methods into a mathematical structure, a generalized framework for cartographic modelling is developed. Within this framework, users logically order primitive operators on map variables in a manner analogous to traditional algebra and statistics. This paper describes the fundamental classes of operations used in computer-assisted map analysis. Several of the procedures are demonstrated using a fourth-generation computer language for personal computers.     

Parallel polygon line shading: the quest for more computational power from an existing GIS algorithm

Abstract

Utilising the powerful resources of a parallel computer has become a technique available to the GIS software engineer for increasing the performance of such complex software systems. This paper discusses the effectiveness of both automatic and manual parallelising techniques with a view to making an assessment as to whether the inherent sequential structure of GIS software is a detrimental factor inhibiting the use of such techniques. With the aid of the Scan Line Fill (SLF) algorithm in GIMMS, it has been shown that whilst automated parallelization has no merits in this case, a significant performance benefit can be achieved with algorithm redesign at the macro level to exploit the natural geometric parallelism inherent within the algorithm. However, the results illustrate that the full potential of this approach will not be appreciated until the I/O bottleneck is completely overcome, as opposed to merely avoided.     

Database design for a multi-scale spatial information system

Abstract

Growth in the available quantities of digital geographical data has led to major problems in maintaining and integrating data from multiple sources, required by users at differing levels of generalization. Existing GIS and associated database management systems provide few facilities specifically intended for handling spatial data at multiple scales and require time consuming manual intervention to control update and retain consistency between representations. In this paper the GEODYSSEY conceptual design for a multi-scale, multiple representation spatial database is presented and the results of experimental implementation of several aspects of the design are described. Object-oriented, deductive and procedural programming techniques have been applied in several contexts: automated update software, using probabilistic reasoning; deductive query processing using explicit stored semantic and spatial relations combined with geometric data; multiresolution spatial data access methods combining poini, line, area and surface geometry; and triangulation-based generalization software that detects and resolves topological inconsistency.     

Interactive GIS for environmental risk assessment

Abstract

Geographical Information Systems can be used for processing spatial data to assess the risks of environmental contamination. Their use depends upon the amount and quality of available data, the models for interpolation and calculation of health risk, data processing procedures and interactivity. In this study, it is shown that interactive use of GIS is important for obtaining physically relevant results. Three forms of interactivity are distinguished: interactivity by means of user interfacing, interactivity requiring additional information outside GIS and interactivity when changing the use of GIS. Three stages in which interaction with GIS are crucial can be distinguished: application of geostatistics, choice of appropriate models, and decision making. This study focuses on three cases in The Netherlands dealing with soil contamination and soil stress analysis and with implications for risk assessment in which interactivity within GIS is analysed. Emphasis is given to contour volumes of polluted soil, to combine GIS with deterministic models and to apply land use scenarios. Finally, there is a discussion of how some forms of interactivity could be replaced by expert systems.     

Performance evaluation and work-load estimation for geographic information systems

Abstract

Agencies acquiring GIS hardware and software are faced with uncertainty at two levels: over the degree to which the proposed system will perform the functions required, and over the degree to which it is capable of doing so within proposed production schedules. As the field matures the second concern is becoming more significant. A formal model of the process of acquiring a GIS is presented, based on the conceptual level of defining GIS sub-tasks. The appropriateness of the approach is illustrated using performance data from the Canada Land Data System. It is possible to construct reasonably accurate models of system resource utilization using simple predictors and least squares techniques, and a combination of inductive and deductive reasoning. The model has been implemented in an interactive package for MS-DOS systems.     

A geographical information system for some Mediterranean benthic communities

Abstract

This paper describes a regional geographical information system (GIS) for some Mediterranean benthic communities. The area covered by the GIS lies between the cities of La Ciotat and Giens in southeast France. The distinctive characteristics of this GIS compared with others usually described in the literature, are that all its layers describe the same theme but as seen at different moments with different scales and techniques used by different oceanographers. A method was devised to synthesize, on a pixel basis, the content of all these layers. Each pixel within each layer is weighted with a function relating to the year of survey, the sampling technique and the scale of the original map corresponding to that layer. The synthesis map is composed of the highest weighted values found in the set of layers. Also at each pixel, conflicts between the contents of layers are quantified and mapped.