摘要:

In order to handle the ever increasing amount of digital data efficiently, methods and techniques for automation have to be available. A key issue is the use of knowledge-based systems to interpret the data and operate on it in an automatic way. Interpretation requires knowledge about the underlying concepts in the data. Providing the necessary knowledge, however, is a bottleneck in automation. In this paper, an approach to semi-automatic knowledge acquisition is described. The knowledge is derived from given example data using supervised machine learning. An application of the approach in the domain of the interpretation of unstructured spatial data is given, and possible further applications are outlined.

ISSN:1365-8816    

DOI:10.1080/136588100240930

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper analyses the accuracy of count data transferred from a zonal system to an incompatible zone through the areal weighting interpolation method. To treat a variety of situations in a theoretical framework, stochastic models representing areal weighting interpolation are developed. The relationship between the accuracy of estimates and the size of source zones is analytically investigated by use of a proposed model. The results strongly suggested that smaller zones give better estimates on a wide range of zonal systems. The effect of the shape of source zones and the target zone on estimation accuracy is also numerically examined, and is also found to be significant.

ISSN:1365-8816    

DOI:10.1080/136588100240949

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper presents a model for describing the positional error of line segments in geographical information systems (GIS). The model is based on stochastic process theory with the assumptions that the errors of the endpoints of a line segment follow two-dimensional normal distributions. The distribution and density functions of the line segments are derived statistically. The uncertainty information matrix of line segments is derived to indicate the error of an arbitrary point on the line segment. This model covers the cases where two-end points are correlated to each other and points on the line segment are stochastically continuous to each other. The model is a more generic error band model than those previously developed and is called the G-Band model.

ISSN:1365-8816    

DOI:10.1080/136588100240958

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper presents a new method for assessment of error in digital vector geographic data, where the features represented can be modelled closely by fractal geometry. Using example hydrological data from Ordnance Survey of Great Britain maps at a range of scales, a resolution smaller than which the digital representation of the feature does not exhibit fractal characteristics can be calculated. It is proposed that this resolution reflects the minimum ground resolution of the map, which in turn can be related to the source map scale.

ISSN:1365-8816    

DOI:10.1080/136588100240967

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The application of existing desktop geographical information systems (GIS) to the assessment of accessibility by public transport has been investigated. Two approaches to the measurement of accessibility aggregate accessibility measures and the space-time geography framework are described. It is suggested that isochrones (lines of equal travel time) are a natural way to combine these approaches in a GIS setting. A desktop GIS application has been developed which can automatically generate isochrones for travel by public transport. The application successfully copes with the complexity of the public transport of a large city (Glasgow), comprising bus, rail, and underground services. Journeys may include an initial walk to a public transport stop, several interchanges between services of the same or different modes, and a final walk. Options provide for plotting isochrones for journeys by bus only or train only; and for exact or approximate isochrones, the latter generated more quickly. The application is described in some detail, and assessed. Sample outputs are presented, including an example involving further processing of isochrones to produce a constrained accessibility map, which demonstrates the generality of this approach.

ISSN:1365-8816    

DOI:10.1080/136588100240976

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:1365-8816    

DOI:10.1080/136588100240985

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor