The Research And Realization Of Contours Drawing Based On MapX

The isohyetose is a line on which all of points have equal rainfall; It was drew according to the once rainfall or period rainfall obtained from the meteorologic station. It is the important reference for all levels of government and flood prevention departments to make decision, owing to its visuality and legibility.This thesis designs and realizes a system which can draw of isohyetose automatically based on the Triangulated Irregular Network (TIN) model, and solved the following problems: the automatic degree for drawing, analyzing, printing contours is not high at present; the efficiency for drawing and analyzing contours maps is not great, and so on.This thesis has firstly done comprehensive research on the related techniques about contours includes: COM GIS technology, MapInfo technology and spatial database technology; and then compared the methods of building up grid through discrete points on the flat surface, made sure the TIN method according to the terrain characters of Three Gorges, and laid a strong emphasis on the study of how to construct the triangulated network; then researched computing, tracing, smoothing and noting equal-points. The interpolation arithmetics which are often used has been introduced and compared. Finally an example about exploiting contours-drawing system on the base of MapX has been given. During this example, the method about creating layers and drawing lines on the MapX has been introduced, and the realization of the arithmetic has been detailedly presented. The contrasting figures and analysis results have also been presented.