Contour line is a kind of map symbols

with which 3D terrain can be recorded on 2D map. Map users know the elevation of terrain with the change of contour line. The changes of contour line means local change and whole change. The latter is also called shape change

and it contains more information of terrain. There are many studies on local change of contour line

and a lot of achievements have been made

such as curvature analysis

dominant points detection

and so on. There are little studies on whole change of contour line

which leads to some problems related to whole terrain remaining unsolved

After studying on shape change of contour line deeply

the author concludes the similarity rule for shape change of contour lines. It provides a new way to interpolate contour line with two neighboring contour lines

Besides

the methods put forwards in this paper can be used to reconstruct 3D terrain surface with contour data. Experimental results show that the new methods can interpolate contour line effectively.