The two objectives of this study are to compare the performances of different data fusion techniques for the enhancement of urban features and subsequently to improve urban land cover types classification using a refined Bayesian classification. For the data fusion, wavelet-based fusion, Brovey transform, Elhers fusion and principal component analysis are used and the results are compared. The refined Bayesian classification uses spatial thresholds defined from local knowledge and different features obtained through a feature derivation process. The result of the refined classification is compared with the results of a standard method and it demonstrates a higher accuracy. Overall, the research indicates that multi-source information can significantly improves the interpretation and classification of land cover types and the refined Bayesian classification is a powerful tool to increase the classification accuracy.

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Central places: The rise and crisis of a concept in geography and spatial planning This paper deals with the history of central place theory, as conceived by W. CHRISTALLER in 1993, in geography and spatial planning (regional policy and regional planning). On the basis of this retrospective the current importance of central place theory in research and of the central place concept (derived from central place theory) in spatial planning will be discussed. Aided by a five-step arrangement of development phases, the history of central place theory in geography is reconstructed. Amongst others, the belated adoption and the differences of empirical and theoretical research between German-speaking countries and North America will be dealt with. At present central place theory does not play an important role in pure research and is unlikely to do so in the future. Those areas that it was originally devised for now have at their disposal more effective theoretical concepts which are also closer to reality. This holds good for research on retailing as well as for the geography of services and for urban systems research. This discussion is followed by an analogous examination of the rise of the central place concept in (West) German spatial planning. The central place concept was introduced into the FragestellungBereits ein flüchtiger Blick durch die geographischen Fachzeitschriften läßt erkennen, daß ,Zentrale Orte' in der wissenschaftlichen Geographie -zumal in Deutschland -eine besondere, wenn auch durchaus ambivalente Rolle spielen: Walter CHRISTALLERS Theorie der Zentralen Orte -das war jener originelle, geradezu geniale Theorieentwurf, der 1933, zur gleichsam historisch falschen Zeit, erschien und der von der damals herrschenden Geographie in seinem Anliegen und seiner fachinnovatorischen Tragweite kaum richtig verstanden wurde. Erst über den Umweg des skandinavisch-angloamerikanischen Sprachraums wurde die Theorie in den 60er und 70er Jahren zum Leitkonzept der quantitativ-theoretischen ,Neuen Geographie'.Ihre bemerkenswert späte, aber dann um so wirkungsvollere Akzeptanz läßt sich wohl nur wissenschaftspsychologisch erklären. In den Jahren des wissenschaftstheoretischen Paradigmenwechsels um 1970, als die komplexgeplagten Geographen aus den Niederungen ihres Gelände-Empirismus neidvoll zu den definition of objectives of regional planning in the "old" federal states between 1968 and 1975 and in the "new" states after the German unification (1990).However, the central place concept has been on the defensive for several years now. The objections brought forward will be identified and reviewed. The refusal of universal validity of the concept is shared here. Nevertheless, the concept is still important today, mainly for two reasons: firstly, it lends itself as an instrument for regulating spatial patterns of developments in the retailing sector, thereby helping to avoid unacceptable developments here. Secondly, it forms an important building stone for the planning of settlement structures which are aligned with the pri...

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The aim of this study is to compare the changes that occurred in the main urban landcover classes of Ulaanbaatar city, Mongolia, during a centralized economy with those that occurred during a market economy and to describe the socio-economic reasons for the changes. For this purpose, multi-temporal remote sensing and geographical information system (GIS) data sets, as well as census data, are used. To extract the reliable urban land-cover information from the selected remotely sensed data sets, a refined parametric classification algorithm that uses spatial thresholds defined from local and contextual knowledge is constructed. Before applying the classification decision rule, some image fusion techniques are applied to the selected remotely sensed data sets to define the most efficient fusion method for training sample selection and for defining local and contextual knowledge. Overall, the study indicates that during the centralized economy significant changes occurred in a ger area of the city, whereas during the market economy the changes occurred in all areas.