Because of its predominant capability

TIN (triangulated irregular network) has been widely used in the simplification of terrains represented as height field.During the generation of TIN

selection of input points is the key to the approximation quality of simplified terrains.Usually

the input point is selected according to the importance measure on each point

so research on the calculation of importance measures has attained more and more attention.Based on analysis and comparison of traditional importance measures

we put forward a new importance measure based on local entropy.The results demonstrate that the local entropy criterion has a better performance than any traditional method.In addition

it can effectively conquer the "short sight" problem in previous methods.