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The XIXth International Congress of Photogrammetry and Remote Sensing was held at the Amsterdam RAI International Exhibition and Congress Centre, the Netherlands, from 16th to 23rd July 2000. Reports are given on the Congress as a whole, including the General Assembly, some Technical Commission activities and the Congress Exhibition. Papers from the Congress are published in the International Archives of Photogrammetry and Remote Sensing, 33.

This paper describes an improved algorithm for fuzzyc-means clustering of remotely sensed data, by which the degree of fuzziness of the resultant classification is decreased as comparing with that by a conventional algorithm: that is, the classification accuracy is increased. This is achieved by incorporating covariance matrices at the level of individual classes rather than assuming a global one. Empirical results from a fuzzy classification of an Edinburgh suburban land cover confirmed the improved performance of the new algorithm for fuzzyc-means clustering, in particular when fuzziness is also accommodated in the assumed reference data.

This paper provides a brief introduction to the methods for generating fuzzy categorical maps from remotely sensed images (in graphical and digital forms). This is followed by a description of the slicing process for deriving fuzzy boundaries from fuzzy categorical maps, which can be based on the maximum fuzzy membership values, confusion index, or measure of entropy. Results from an empirical test preformed in an Edinburgh suburb show that fuzzy boundaries of land cover can be derived from aerial photographs and satellite images by using the three criteria with small differences, and that slicing based on the maximum fuzzy membership values is the easiest and most straightforward solution. This, in turn, implies the suitability of maintaining both a crisp classification and its underlying certainty map for deriving fuzzy boundaries at different thresholds, which is a flexible and compact management of categorical map data and their uncertainty.

This paper endeavours to put the discussion on errors and uncertainties in geographical information systems (GISs) in a more systematic way by examining the strength and weakness of discrete objects and continous fields, the two distinct schools of spatial data modelling. In doing so, it argues that neither discrete objects nor continous fields alone provide objective and complete representations of highly complex geographical phenomena, though there are good reasons for asserting that continuous fields are better suited to modelling spatial dependence, heterogeneity and fuzzines significant in geographical reality than discrete objects. Thus, there seems to be merit in adopting an integrated model incorporating analytical capabilities of fields and generalization functions of objects, for which extended TIN (triangulated irregular network) models along with their duals (Voronoi diagrams) provide a pragmatical solution.

Fuzzy approaches are of increasing importance for representing and handling geographical area and boundary delineations. This paper evaluates three different approaches that may be applied to derive fuzzy maps of land cover obtained by photogrammetry from aerial photographs. The three approaches are all spatial interpolation methods, based respectively on distances, on triangulated irregular network (TIN) models and on indicator kriging. For each approach, a set of methods for assessing the accuracies of fuzzy maps has been employed, including the overall classification accuracy, entropy, cross-entropy and divergence. A local Edinburgh suburb was used as a test site where there is a mixture of well-defined and poorly defined locations. It was found that while the TIN model-based approach produces the best empirical results in terms of the overall classification accuracy, entropy and cross-entropy, indicator kriging is theoretically the most sound approach to deriving fuzzy maps of land cover from photogrammetric data, especially when fuzziness is properly accommodated in the assumed reference data.

(1997). The Aberlady Bay coastal landforms and vegetation communities. Scottish Geographical Magazine: Vol. 113, No. 2, pp. 121-126.

SynopsisThe historical formation of the loch is described, using geological and geomorphological evidence. The changing areal dimensions from the seventeenth to nineteenth centuries are discussed using historical cartographic and documentary evidence. Finally, a comparison is made between the results of the three bathymetrical surveys that have now been carried out in an attempt to determine the amount of silting.

(1974). The development of remote sensing: Review article. Scottish Geographical Magazine: Vol. 90, No. 3, pp. 180-184.