Research On Point Cloud Hole Restoration Technology In Mountainous Area Taking Into Account Topographic Feature Line Elements

The restoration of point cloud holes is an important step in the data preprocessing stage of 3D laser scanning technology.At present,most of the mainstream point cloud void repair algorithms interpolate and fill the voids by analyzing the geometric characteristics of point cloud around the void boundary,which is a typical "mathematical thinking" method.The method is applicable to the regular surface cloud hole restoration.For surface irregular point cloud data,this kind of repair method is not ideal.In view of this problem,considering that the terrain element lines(mainly valley lines and ridge lines)as the terrain framework have important images of the geometric characteristics of the terrain,According to the idea of "using geographic thinking to deal with geospatial problems",this paper presents a method of ground point cloud void restoration considering the elements of topographic lines.The main ideas of this method are as follows: Firstly,based on the ground point cloud data,the topographic feature lines,i.e.Valley and ridge feature lines,are extracted by the method of slope analysis and re-classification of GIS,and then transformed into Valley and ridge feature points.Then,based on the extracted ridge feature points,Lagrange interpolation method is used to repair the missing ridge points.Finally,the missing ridge points are edited and inserted into the point cloud file,and the ridge points with valley are repaired on the point cloud data processing platform.Around this technical process,this paper designs three series of comparative experiments to demonstrate and analyze the feasibility of this method.The results showed that:(1)It is feasible to extract the valley ridge feature points of ground point cloud based on slope analysis and re-classification of GIS and to interpolate the valley ridge points of ground point cloud voids based on the extraction of Valley ridge points.(2)The spatial distribution of the precision value of the cloud hole is more obvious than that of the terrain feature lines.(3)Geomagic Studio software platform is better than I-Site Studio software platform in repairing point cloud cavities under the same topographic features without considering Valley ridge features.(4)It is feasible to take the valley-ridge points of slope analysis extraction and Lagrange interpolation to repair the ground point cloud cavities.And on the commercial point cloud data processing software platform Geomagic Studio and I-Site Studio,compared with the conventional point cloud void repair method without considering the valley ridge feature elements,the accuracy of the void repair method with the valley ridge feature points participation is improved.Among them,the improvement effect of Geomagic Studio software platform is more obvious.In summary,the ground point cloud void repair method considering the topographic feature lines is feasible from theoretical deduction to technical implementation,and compared with the traditional void repair method relying on "mathematical thinking",the accuracy is greatly improved.This can be used to repair the holes in complex terrain surface in the future.