摘要:

The potential of geographical information systems for strategic policy analysis is examined and demonstrated by example. One of the necessary conditions for this potential to be realised is the development of integrated data sets that combine economic, production and physical data sets at similar scales. The paper illustrates this potential using examples from a State-wide Resource Information and Accounting System developed by CSIRO.

ISSN:1365-8816    

DOI:10.1080/136588197242112

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Polygonized data, e.g., census tract data, are hard to relate to other factors. We developed a procedure that: (a) dissects a continuous ‘original surface' into discrete polygons, and (b) reconstructs the original surface from the polygons. Five reconstruction algorithms were tested. We conclude that (a) degrade-andrestore techniques are an effective and intuitive way to test restoration skill; (b) resolution is more important than choice of algorithm; (c) results depend on the interplay of the original surface, the polygon mesh, and the restoration algorithm, and (d) sophisticated algorithms such as Kriging are best left to sophisticated users.

ISSN:1365-8816    

DOI:10.1080/136588197242121

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Recent studies have shown that the Vector Product Format (VPF) and most VPF-based products no longer meet the needs of the Modelling and Simulation (M&S) community of the Army, Navy, and Marine Corps. The research presented in this paper addresses some of the deficiencies outlined in these requirement surveys. One of the goals of this research is an Extended Vector Product Format (EVPF) and an EVPF-based product Modelling and Simulation Extended Vector Product (MSEVP). EVPF, which remains within the confines of VPFs static georelational data structure, extends VPF to allow for the efficient storage and access of Triangulated Irregular Network (TIN)-based three dimensional elevation data. Additionally, EVPF permits the efficient integration of terrain elevation data with ground surface features, and provides an elegant method of rendering terrain in three-dimensions. This paper documents the design of EVPF and highlights its salient features. It also reports on our progress toward the design and implementation of an MSEVP prototype. MSEVP is expected to better serve the needs of the M&S community by addressing some of the deficiencies outlined in recent requirement studies. The paper will address: (a)the generation of TIN based three-dimensional terrain data to populate the elevation coverage, (b) the extraction and conditioning of the transportation network to populate the associated coverage and (c) the integration of the transportation and elevation coverages.

ISSN:1365-8816    

DOI:10.1080/136588197242130

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The increasing use of Geographical Information System applications has generated a strong interest in the assessment of data quality. As an example of quantitative raster data, we analysed errors in Digital Terrain Models (DTM). Errors might be classified as systematic (strongly dependent on the production methodology) and random. The present work attempts to locate some types of randomly distributed, weakly spatially correlated errors by applying a new methodology based on Principal Components Analysis. The Principal Components approach presented is very different from the typical scheme used in image processing. A prototype implementation has been conducted using MATLAB, and the overall procedure has been numerically tested using a Monte Carlo approach. A DTM of Stockholm, with integer-valued heights varying from 0 to 59 m has been used as a testbed.The model was contaminated by adding randomly located errors, distributed uniformly within 4 m and 4m. The procedure has been applied using both spike shaped (isolated errors) and pyramid-like errors. The preliminary results show that for the former, roughly half of the errors have been located with a Type I error probability of 4.6 per cent on average, checking up to 1 per cent of the dataset. The associated Type II error of the larger errors (of exactly 4m or 4 m) drops from an initial value of 1.21 per cent down to 0.63 per cent. By checking another 1 per cent of the dataset, such error drops to 0.34 per cent implying that about 71 per cent of the 4m errors have been located; Type I error was below 11.27 per cent. The results for pyramid-like errors are slightly worse, with a Type I error of 25.80 per cent on average for the first 1 per cent effort, and a Type II error drop from an initial value of 0.81 per cent down to 0.65 per cent. The procedure can be applied both for error detection during the DTM generation and by end users. It might also be used for other types of quantitative raster data.

ISSN:1365-8816    

DOI:10.1080/136588197242149

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

As part of the EU-funded SAVIAH project, a regression-based methodology for mapping traffic-related air pollution was developed within a GIS environment. Mapping was carried out for NO2 in Amsterdam, Huddersfield and Prague. In each centre, surveys of NO2, as a marker for traffic-related pollution, were conducted using passive diffusion tubes, exposed for four 2-week periods. A GIS was also established, containing data on monitored air pollution levels, road network, traffic volume, land cover, altitude and other, locally determined, features. Data from 80 of the monitoring sites were then used to construct a regression equation, on the basis of predictor environmental variables, and the resulting equation used to map air pollution across the study area. The accuracy of the map was then assessed by comparing predicted pollution levels with monitored levels at a range of independent reference sites. Results showed that the map produced extremely good predictions of monitored pollution levels, both for individual surveys and for the mean annual concentration, with r2 0.79-0.87 across 8-10 reference points, though the accuracy of predictions for individual survey periods was more variable. In Huddersfield and Amsterdam, further monitoring also showed that the pollution map provided reliable estimates of NO2 concentrations in the following year (r2 0.59-0.86 for n 20).

ISSN:1365-8816    

DOI:10.1080/136588197242158

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1365-8816    

DOI:10.1080/136588197242167

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor