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In the construction of DEM, terrain features (e.g. valleys or stream lines, ridges, peaks, saddle points) are important for
improving DEM accuracy and saw many applications in hydrology, precision agriculture, military trajectory planning,
etc. HASM (High Accuracy Surface Modeling) is a method for surface modeling, which is based on the theory of surface.
Presently, HASM is only used for scattered point's interpolation. So the work in this paper attempts to construct DEM
based on the characteristic terrain information as stream lines and scattered points by HASM method. The course is
described as the following steps. Firstly TIN (Triangulated Irregular Network) from the scattered points is generated.
Secondly, each segment of the stream lines is well oriented to represent stream lines' flow direction, and a tree data
structure (that has parent, children and brothers) is used to represent the whole stream lines' segments. A segment is a
curve which does not intersect with other segments. A Water Course Flow (WCF) line is a set of segment lines
connected piecewise but without overlapping or repetition, from the most upper reaches to the most lower reaches. From
the stream lines' tree data structure, all the possible WCF lines are enumerated, and the start point and end point of each
WCF lines is predicted from searching among the TIN. Thirdly, given a cell size, a 2-D matrix for the research region is
built, and the values of the cells who were traversed by the stream lines by linear interpolation among each WCF lines.
Fourthly, all the valued cells that were passed through by the stream line and that were from the scattered points are
gathered as known scattered sampling points, and then HASM is used to construct the final DEM. A case study on the
typical landform of plateau of China, KongTong gully of Dongzhi Plateau, Qingyang, Gausu province, is presented. The
original data is manually vecterized from scanned maps 1:10,000, includes scattered points, stream lines, contour lines,
precipitous cliff lines of a region of area about 4×5 square km. For simplicity only the former two kinds of data sources
are used. By Comparing with the result from stream-line-constrained TIN and hydrologically correct DEM construction
method Thin plate Spline (TPS, that is implemented as command TopoToRaster in ArcGIS 9.0 and later version)through
visual inspection, HASM gets a more desirable DEM and more reasonable integration of information of the terrain
features. Finally, some challenges and future research about HASM is also given.
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