The methodology of catchment extraction especially from regular grid digital elevation models(DEMs)is briefly reviewed.Then an efficient algorithm,which combines vector process and traditional neighbourhood raster pro...The methodology of catchment extraction especially from regular grid digital elevation models(DEMs)is briefly reviewed.Then an efficient algorithm,which combines vector process and traditional neighbourhood raster process,is designed for extracting the catchments and subcatchments from depressionless DEMs.The catchment area of each river in the grid DEM data is identified and delineated,then is divided into subcatchments as required.Compared to traditional processes,this method for identifying catchments focuses on the boundaries instead of the area inside the catchments and avoids the boundary intersection phenomena.Last,the algorithm is tested with a set of DEMs of different sizes,and the result proves that the computation efficiency and accuracy are better than existent methods.展开更多
This paper proposes a new algorithm for determining the starting points of contour lines. The new algorithm is based on the interval tree. The result improves the algorithm＇s efficiency remarkably. Further, a new str...This paper proposes a new algorithm for determining the starting points of contour lines. The new algorithm is based on the interval tree. The result improves the algorithm＇s efficiency remarkably. Further, a new strategy is designed to constrain the direction of threading and the resulting contour bears more meaningful information.展开更多
基金the National Key Basic Research and Development Program of China(No.2002CB312101 and No.2004CB318206)the Hubei Out standing Young Researchers Foundation of P.R.China(No.2004ABBO18).
文摘The methodology of catchment extraction especially from regular grid digital elevation models(DEMs)is briefly reviewed.Then an efficient algorithm,which combines vector process and traditional neighbourhood raster process,is designed for extracting the catchments and subcatchments from depressionless DEMs.The catchment area of each river in the grid DEM data is identified and delineated,then is divided into subcatchments as required.Compared to traditional processes,this method for identifying catchments focuses on the boundaries instead of the area inside the catchments and avoids the boundary intersection phenomena.Last,the algorithm is tested with a set of DEMs of different sizes,and the result proves that the computation efficiency and accuracy are better than existent methods.
基金Grant from LIESMARS (No.WKL(06)0302)the Basic Research Grant of CASM(No.G7721)
文摘This paper proposes a new algorithm for determining the starting points of contour lines. The new algorithm is based on the interval tree. The result improves the algorithm＇s efficiency remarkably. Further, a new strategy is designed to constrain the direction of threading and the resulting contour bears more meaningful information.
