摘要:

As efforts grow to develop spatio-temporal database systems and temporal geographical information systems that are capable of conveying how geographical phenomena change, it is important to distinguish the elements that are fundamental to scenarios of change. This paper presents a model based on the explicit description of change with respect to states of existence and non-existence for identifiable objects. Such changes are of concern when, for instance, modelling and reasoning about nations that are subsumed through conflict only to return once more at a later time, or about water bodies that fluctuate due to seasonal or climatic change. The basis for tracing these changes is the concept of object identity. Identity, distinct from an object's properties, values, or structure, is that unique characteristic that distinguishes one object from another. Based on a small set of primitives relating to the identity states of objects, we model the semantics associated with change and through a systematic derivation, a complete set of identity-based change operations evolves from the primitives. These operations are basic to the types of change commonly experienced by geographical phenomena and modelled by researchers studying spatio-temporal change. This approach highlights the minimum elements necessary for reasoning about change, namely, object identity, an ordering of identity states, and co-occurrence of identity states.

ISSN:1365-8816    

DOI:10.1080/136588100240813

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper describes an application of fuzzy set theory to perform temporal interpolation in a raster GIS database. Specific fuzzy membership functions have been derived to simulate spatial changes between consecutive snapshots registered in the database. The proposed approach is tested on a very dynamic rural-urban environment of Montreal Metropolitan area in Quebec, Canada, covering the period from 1956 to 1986 with a temporal resolution of ten years. A user friendly software package named FUZZY_TEMP was developed and integrated in the GRASS4.1 environment in order to perform the implementation of the developed concepts.

ISSN:1365-8816    

DOI:10.1080/136588100240822

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Regression is often used in analysis of spatial data to obtain predictive relationships between variables. The assumption that the errors from the regression model are statistically independent will often not be plausible, due to spatial dependence in the sources of error. This is a problem for the regression analysis in that the resulting estimate of the standard deviation of the errors from the model is biased (downwards) which invalidates confidence limits on predictions made with the model, and which could lead to a false conclusion that the regression is statistically significant. While the estimates of the regression coefficient(s) are not necessarily biased they are not minimum-variance estimates when the errors are correlated.

ISSN:1365-8816    

DOI:10.1080/136588100240831

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

To assess the implications of sea level rise along the English east coast, the Arc-Info GIS package was used to determine coastal vulnerability to flooding. Results from oceanographic and climatic research were combined with data on sea defences, elevation values, and patterns of landuse. A risk assessment model was developed to estimate flood return periods according to different climate change scenarios for the years 2050 and 2100. Flood risks were modelled as a function of the height and condition of sea defences, land elevations, and subsidence rates. The ‘house equivalent’ concept was used to estimate damage costs of flood events in a future climate-changed environment. For the year 2100 the model predicts significant increases in flood damage costs. However, the results indicate the considerable uncertainty associated with sea level rise predictions. Our findings may potentially be of both academic and practical interest, but will be of little practical significance to coastal managers and planners if they cannot use them. To illustrate how this might be facilitated, their incorporation into an easy to use prototype Decision Support System (DSS) is outlined. The development of such systems is possibly the next major challenge for the application of GIS technologies to the coastal zone.

ISSN:1365-8816    

DOI:10.1080/136588100240840

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The GIS literature abounds with strategies to guide the development of a corporate GIS as a single project but lacks discussion on the long term management of the GIS. This paper documents a recent study into GIS development in a state department over an 18-year period. It applies the productional perspective of GIS to model long term GIS development diagrammatically and identifies five patterns of GIS development. The outcomes reveal some long term characteristics of a corporate GIS, based on which a three-stage approach is developed to guide the long term development of an ideal corporate GIS.

ISSN:1365-8816    

DOI:10.1080/136588100240859

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:1365-8816    

DOI:10.1080/136588100240868

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor