Raster_StreamExtractionService - This service could be used to extract stream network from digital elevation model (DEM). It provides three methods for deriving stream network.
curvatureBasedMethod - Derive stream network from DEM based on topographic curvature. Use morphology based algorithm to compute curvature and flow accumulation, then threshold them to derive stream network. The processing could be slow and lengthy.
flowDirectionBasedMethod_GRASS - Derive stream network from DEM based on flow direction. Use r.watershed hydrological module in GRASS GIS software to compute flow accumulation, select a treshold to extract stream network from the accumulation.
Derive stream network from DEM based on topographic curvature. To improve the speed of calculation, curvature is approximately derived by convoluting DEM with a 9×9 Laplacian filter.
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