B.S. Daya Sagar: Mathematical Morphology in Geomorphology and GISci

Abstract

I read with great interest B.S. Daya Sagar’s book “Mathematical Morphology in Geomorphology and GISci”. Indeed, the definition ofMathematicalMorphology concepts and tools has drawn inspiration from topographical, geological and geomorphological analogies: images are often considered as topographic surfaces and the names of certain basic or more complex operators (erosion, watershed transform, waterfalls, etc.) clearly show their affiliation with the phenomena that gave them rise (although we should be careful with these analogies). It is therefore interesting to see what can be achieved using mathematical morphology in a field of earth sciences that inspired it. D. Sagar’s work is very dense (500 pages). It is divided into 14 sections, much of which is devoted to the description of case studies using morphological operators. The second chapter deals with the recall of definitions of mathematical morphology concepts and tools used by the author. A whole chapter is also devoted to the description of analyzed data: digital elevation models (DEM), digital bathymetric maps (DBM), satellite images, thematic maps, and more. This is particularly worthwhile as it is very important to always keep in mind the true nature of the images analyzed, so as not to lose touch with the physical reality and the scale of the phenomena studied. Beside those real data, D. Sagar also uses fractal representations simulated using morphological operators (this section leaves the reviewer a little confused because the fractal approach seems to be only loosely related to the mathematical morphology field). The other chapters (4–8) present a compilation of case studies illustrating the use of various mathematical morphology tools for feature extraction (mountains, piedmonts, valleys, water bodies, river networks, etc.) and characterization (shape, size, size distribution). The last part of the book (Chaps. 9–14) describes tools quantifying the spatial relationships between these features and/or clusters of features, with a final