Study On The Algorithm Of Contour Curvature In Digital Topographic Map

Digital Terrain Analysis (DTA) has developed into a subject which is based onDigital Elevation Model (DEM). Constructing DEMs from contours is the most popularway of getting DEMs. One of the basic problems is to define the resolution of DEM.Contour curvature calculation is the foundation of defining a proper resolution.Systematic research on contour curvature’s concept and method of calculation hasbeen done in this article. The propose of this article is to provide a scientific basis forquantitative analysis of complexity and quantity of information of contours, and definingof the best resolution. Main conclusions are as follows:(1) Analysed concept and definition of contour curvature, and summarized therelationships between contour curvatrue and other curvatures (profile curvature, plancurvature and tangent curvature).(2) Propoed the circle fitting method of calculate contour curvature on contoursbased on mathematical definition of curvature. Programmed the circle fitting method andalgorithm of contour curvature based on grid DEM.(3) Compared vector contour curvtaure to series resolutions grid contour curvaturein Xinannangou sample terrain data. Found that2.5m DEM has contained more terraininformation of contours in the second sub-region of Loess Plateau, which meets formerresearch.(4) Analysed contour curvature on different complex terrain area, found that contourcurvature has a close relationship with gully density, but not with mean slope of researcharea.