The aim of this study is to show the rapid growth of some agglomerations, in a country such as Greece. For that purpose, we use satellite images. The chosen method needs two spectral variables: the brilliance index and the vegetation index. The calculation of each of the two variables occurs at two different times, from two Landsat pictures covering the agglomeration of Athens and a part of the plain of the Mésogée. These two indices constitute the two components of a vector which discribes the direction and the amplitude of the change between the two times. The results are visualized with different colours which characterize the type of change. This method is conclusive: it enables one to show very precisely changes in the surfaces. Nevertheless, its weak point is the difficulty in defining the threshold between the places which have changed and the ones which have stayed stable.