Change detection from remote sensing data is often done by simple overlay of classified maps. However, such analyses can contain a significant proportion of boundary errors, especially when combining data from different sensors. This paper presents a protocol that allows reliable post-classification comparisons by taking into account classification accuracies, landscape fragmentation, planimetric accuracies, pixel sizes and grid origins. The proposed protocol has been applied, with little extra effort, in a fragmented agricultural Mediterranean zone using MSS (1970s) and TM (1990s) images. Applying the protocol, change detection had an accuracy of 85.1%, while for a direct overlay it was only 43.9% accurate. The drawback of this method is that it reduces the useful area of comparison. As the accuracy of individual classifications is critical, the paper also describes and tests a hybrid classifier that combines an unsupervised classification approach with training areas. This approach has proved more successful than maximum likelihood classifiers.

Swimming pools are together an exemplificative outcome of urban sprawl and an indicator of socio-spatial polarizations in metropolitan regions. A comparative analysis of the spatial distribution of pools in three Mediterranean cities (Barcelona, Rome and Athens) provides an alternative reading of recent urbanization in southern Europe, questioning the supposed homogeneity in socioeconomic patterns and processes across the region. In the present study, the socio-spatial structure underlying dispersed urban expansion in these three cities was studied using 53 background indicators at the spatial scale of municipalities. Four indicators were proposed to study variability in the spatial distribution of pools. Relevant differences between cities were observed in the density of pools, reflecting heterogeneous patterns of dispersed urbanization and class segregation: socioeconomic polarization in Athens, settlement scattering and social mix in Rome and a more balanced socio-spatial structure in Barcelona. The spatial distribution of pools in the three cities was found associated with different socioeconomic factors, outlining the role of spatial disparities between high-income and low-income neighbourhoods, the diverging economic base and place-specific attributes. Results from Barcelona, Rome and Athens case studies provide contrasting views of the relationship between class segregation and the local socioeconomic context. The resulting patterns of sprawl reflect distinct urban models belying the supposed homogeneity of the ‘Mediterranean city’ archetype.