Finding the structure of a satellite image
Philippe Marthon, Bruno Paci, Eliane Cubero-Castan · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1994
This is a method for the analysis of a satellite image (SPOT data) by radiometry and geometry. This method consists of three steps. First of all, image outlines are obtained by applying the Watershed algorithm to the gradient modules of the image. Because of the memory size required to analyse a whole image, we must break it down into a set of small images. However, this technique introduces some extra outlines which can be detected and removed easily. Then, we extract the vertex graph: each node represents a pixel of the outline with at least three neighbouring pixels. An arc between two nodes shows the presence of an outline between two closely related pixels. Finally, the region tree is computed. The tree structure allows the coding of sub-regions. Each region is described by a polygonal approximation of its boundary. This method has been successfully tested for the extraction of the agricultural area of King's Lynn (UK).