Research And Application Of Terrain Feature Line Extraction Method Based On DEM

Terrain feature line extraction as the basic of geographic information technology plays a significant role,it is well applied in sample-based terrain synthesis fields and other fields.There is much important terrain feature information in the digital elevation mode,among which the ridge and valley lines are the most important characteristic lines.The result of Sample-Based Terrain Synthesis System is directly affected by the characteristics of the ridge line and the valley line extracted from the terrain.Therefore,in this paper,a new explicit controllable terrain feature line extraction algorithm is designed for the improvement of the terrain feature line extraction method,and the experiment is compared with the existing algorithm.At the same time,the algorithm of this paper is applied to a set of sample based terrain synthesis system.The innovation of this paper is as follows:(1)A thinning algorithm based on saliency is proposed.This algorithm is based on the characteristic of the feature point.Thus,the feature points with more obvious characteristic is retained,when selecting the to be removed feature points in characteristic line prototype process.And the refined characteristic lines could maintain strong characteristics.At the same time,compared with the traditional thinning algorithm,this algorithm can maintain better characteristic line shape after the refinement.(2)A loop detection and breaking algorithm is proposed.The basis of this algorithm is the order of scan line,the non-characteristic pixel is numerically filled via the depth-first traversal method so that the non-characteristic pixels are divided in the form of regions.The loop area and non-loop area are divided through the classification of the regions.And the number of non-feature points within the region statistics,could classify large loops and small loops.Finally,according to the detection of each small loop area boundary line,the screening of the weakest boundary line is eliminated,so that the removal of the small loop and the retention of the large loop are realized.(3)A feature graph decomposition and feature line filtering algorithm is proposed.This algorithm divides the feature graph with the characteristic line(except the endpoint,the degree of branch's other points is two)as the basic unit,and selects the most similar characteristic branch from the strongest characteristic branches to form the characteristic line.Compared with the traditional method,this method not only avoids the excessive extension of the characteristic line,but also can be applied to the feature graphs with loop,and makes characteristic lines closer to the actual observation.Based on the above innovation,this paper designs and implements a terrain feature line extraction system,which fills the gaps in the traditional methods that do not recognize the special terrain,and the extracted feature lines are more realistic.At the same time,a sample based terrain synthesis system is implemented.The terrain feature extraction method proposed in this paper is applied to the system,and more suitable feature matching blocks have been found in the synthesis process.