THE METHODS OF EXTRACTING WATER INFORMATION FROM SPOT IMAGE

摘要

Some techniques and methods for deriving water information from SPOT -4 (XI) image were investigatedand discussed in this paper. An algorithm of decision-tree (DT) classification which includes several classifiers based onthe spectral responding characteristics of water bodies and other objects, was developed and put forward to delineate wa-ter bodies. Another algorithm of decision-tree classification based on both spectral characteristics and auxiliary informa-tion of DEM and slope (DTDS) was also designed for water bodies extraction. In addition, supervised classificationmethod of maximum-likelyhood classification (MLC), and unsupervised method of interactive self-organizing dada analy-sis technique (ISODATA) were used to extract waterbodies for comparison purpose. An index was designed and used toassess the accuracy of different methods adopted in the research. Results have shown that water extraction accuracy wasvariable with respect to the various techniques applied. It was low using ISODATA, very high using DT algorithm andmuch higher using both DTDS and MLC.