MULTISCALE SPATIAL RELATION EXTRACTION OF A REMOTELY SENSED WATERLINE IN A MUDDY COASTAL ZONE WITH CHONGMING DONGTAN AS AN EXAMPLE

Abstract. To address the difficulty of waterline extraction in areas with gentle slopes in the muddy coastal zone, Chongming Dongtan in the Yangtze River estuary is selected as the research object. This paper analyzes the spatial relationship of the waterline in Landsat images at three spatial scales, gives a method for numerically calculating the spatial relationship characteristics at different spatial scales and the application means in waterline extraction, and constructs a model for waterline extraction from Landsat images using the multiscale spatial relationship. Finally, the execution efficiency and positioning accuracy of the multiscale spatial relationship waterline extraction model are quantitatively evaluated. The results show that the spatial relationship is effectively used to solve the problem of discontinuous extraction of a weak waterline in the muddy coastal zone, and the waterline recognition ability for remote sensing images is significantly improved. The position accuracy of waterlines obtained by the improved method can reach 12.4 meters. Compared with other methods, this method shows great advantages in terms of automation, waterline continuity, and positioning accuracy and provides technical support for the use of remote sensing technology to study the dynamic changes in coastal zones.