Research On The Point Cloud Filtering Of Image Matching And Its Application

In the era of rapid development of information and intelligence,aerospace photogrammetry and remote sensing technology has been greatly developed as an important means to obtain location and semantic information of the earth surface.In this context,remote sensing images(including domestic high-resolution mapping satellite images,UAV images,etc.)that can be obtained for surveying and mapping geographic information products have also been widely used in recently years.The Digital Elevation Model(DEM)is one of 4D(DEM,DOM,DLG,DRG)products and has been widely used in fields such as surveying and mapping,land and national defense construction.However,the point cloud data obtained by the traditional photogrammetry—images matching technology still has a poor levels of automation when extracting DEM.The algorithm has poor generality when dealing with the different terrains,and it takes a lot of manpower and material resources in the DEM post-processing.In the above question,this paper studies the aerial image matching point cloud filtering.In addition,combined with the specific project being implemented in china at this stage(the third national survey,global mapping,etc.),how to apply product of DEM filtering to effectively solve the problems of distortion and smear in the production DOM,this paper also explores the operation mode and puts it into practice.This main research contents and conclusions of this paper are as follow:(1)Aiming at the aerial image matching point cloud,a new method was proposed for point cloud filtering.Firstly,it utilizes an image classification method that combines multiple source information and introduces a new classifier,and then knowledge guidance of using its classification results is used in point cloud filtering,that is to say,removing non-ground points is carried out by overlapping a thematic map of classification with a point cloud.Finally,point cloud filtering is implemented and obtain the DEM.The Aerial image is used for an experiment that include dense image matching and filtering test.The Aerial image is used for an experiment that include dense image matching and filtering test.The quantitative evaluation results show that the method can reduce the manual post-processing by a long way and improve the DEM accuracy further more.(2)Aerial images were selected to match the point cloud and this paper employed latest cloth simulation technology for point cloud filtering.Combined with the principle of the algorithm,that is on the basis of point cloud turning upside down,and with a piece of cloth that conforms to the law of Hooke's law and is affected by internal and external forces,filtering was done by comparing threshold distance between cloth and point cloud.Test was carried out and the results showed that the CSF algorithm can obtain better filtering effects for point clouds of different terrain scenes.Compared with traditional algorithms,it has advantages in filtering precision and algorithm efficiency.(3)It is the basis for resource and environmental monitoring and census of national conditions when orthophoto is produced as the base map in land survey.Aiming at the large number of distorted areas existing in the orthorectified image,especially the road area,this paper proposes a new method.That is to say,Real-time local orthorectification is carried out by editing DEM which is in the road distortion area.It is shows that the method achieves a rapid rectify of the image road distortion area,and there is no obvious misalignment of the road area of the edge after rectify by the high-resolution satellite imagery of the GF-2 and TRIPLESAT-2 experimental data.In addition,through a certain number of control points in the road area,comparing the accuracy of Local orthorectification before and after,it also shows that the method significantly improves the rectify accuracy of the road distortion area,and meeting the requirements of relative Orthophoto production accuracy.In summary,aimed at the aerial image matching point cloud,this paper studies the DEM filtering method for production and its related problems.Combined with the specific production requirements,the application of mapping satellite DEM in the typical ground feature correction of DOM is given,and an efficient mode of operation was given and puts it into practice.