ABSTRACT
Ascendant hierarchic classification is based on the measure of a distance, such as Euclidean, computed for each of the N pixels having different spectral characteristics. A dendrogram is drawn representing various phases of classification, placing pixels on the abscissa and a value similar to an intergroup distance on the ordinate. A dendrogram can be analysed systematically. Two groups are chosen and the geographic spatial distribution of each is observed on the image. The purpose of a legend is to give meaning to the classification created. Each group is assigned a name with reference to a semantic or a geographic model. The possibility offered by image processing to immediately and interactively see the dendrogram, the number of groups chosen and the corresponding spatial result is of great significance in interpretation of classification. The digital characteristics of water can be recognised from the fact that digital numbers are the smallest in band 3, but not in 1 or 2.
