The True-color Point Cloud Generation Technology Based On Registration Of Airborne LiDAR Point Cloud And Image

With the rapid development of airborne laser scanning measurement technology in recent years,it has a broad application prospect in digital city,disaster monitoring,coastal engineering,forestry investigation and so on.However,this technique can only obtain the 3D spatial coordinates and the reflection intensity information of the target object and has no ability to acquire the real texture information of the object.With the rapid development of digital imaging technology and image sensor,it is not hard to obtain high-definition visible image.Image processing and fusion technology is widely used in machine vision and aerial remote sensing field.The target object texture information of the image is complementary to the 3D information obtained by laser scanning technology.Based on the airborne laser scanning technology and aerial imaging technology,this paper designs and implements a set of airborne LiDAR system.After that,the research on the registration and fusion algorithm of 3D point cloud data and image data has been done.Finally,3D real color point cloud image with real texture information is obtained.First of all,base on the embedded technology,this paper designs and implements a set of highly autonomous and high-precision airborne LiDAR system.The system is mounted on a small unmanned aerial vehicle(UAV)to realize real-time synchronization acquisition of laser scanning data,aerial image data,attitude data and global positioning data.According to the data obtained,the LiDAR point cloud generation,filtering and display are realized on the ground station.Secondly,in this paper,the generation principle of Li DAR point cloud and the imaging model of the camera are analyzed in detail.After that,the data preprocessing technology of point cloud and image is described from point cloud splicing,point cloud projection,aerial orthophoto and image mosaic.Finally,in order to obtain the real color 3D point cloud,this paper designs two kinds of registration and fusion algorithm of 3D point cloud and aerial image.In view of the fixed installation of scanner and camera,this paper designs the joint calibration method of laser scanner and camera based on artificial reflection marks.By resolving the external transformation relationship between the laser scanner coordinate system and the camera coordinate system,the two are synchronized in the space.For conditions that do not have calibration conditions,an algorithm based on image registration is designed.The point cloud ortho-projection image is matched with the aerial orthopthoto image to obtain the mapping membership between the 3D point coordinates and the image pixel coordinates.Finally,registration fusion between point cloud and image are realized.In addition,the airborne LiDAR system is used to acquire data in the actual flight scanning experiment.Based on the real data,the paper validates the registration fusion algorithm and analyzes the final results.The Li DAR system and the registration fusion algorithm has been experimentally proved to be stationary and practical.