Aerial Triangulation Without Ground Control Point Based On GNSS PPK Technology

How to reduce or eliminate the need for ground control points and directly obtain the external orientation elements of the photos has always been the goal pursued by photogrammetry workers.Traditional aerial photogrammetry,like the deployment of control points,takes more manpower and time.If an aircraft equipped with a POS(Position and Orientation System)is used,the cost and load of a high-precision IMU(Inertial Measurement Unit)restricts its popularity.The research focus of this paper is mainly the topological relationship between point and line planes in aerial triangulation,non-control point algorithm based on GNSS PPK(Post Processed Kinematic).This data comes from the Moon Island project of Wuhan Aerospace Vision Technology Co.,Ltd.This project is based on the CW-10 unmanned aerial vehicle and aerial camera with 35 mm focal length.It belongs to the category of GPS-assisted aerial triangulation and processes data according to the algorithm requirements.The main contents of the study are as follows:(1)Study the topological relations of point-line surfaces involved in aerial triangulation.Through the analysis of different routes and lateral overlapping degrees,eight connected and fourteen connected relationships such as the main point and the image point are listed,and a uniform number is generated for the points of the same name generated in the measurement area,that is,the image connection point matrix.The relationship between the three main points,such as the main point,the image point,and the same name,is further deduced.Any two point numbers can be used to push out the data of the remaining point.Experiments show that the topological relationship of aerial triangulation provides the logical foundation for the algorithm.(2)Research on the controlless point algorithm based on GNSS PPK technology.From the original data—the aerial camera interior orientation elements,the GNSS antenna center image space coordinates and the ground photogrammetry coordinates,and the photo image with the same name and point image coordinates,using spatial similarity transformation and stereoscopic image pair space front intersection,an approximate value of the ground coordinate of the ground point corresponding to the outer point of the image is approximated.Then,the equation of the cumulative law is solved by the beam method area network aerial triangulation method equation and the analytical absolute orientation law equation,and judge the corrected image outside the orientation element correction,the same name point corresponding to the ground point of the ground coordinates correction is consistent with the limit,if it doesn't match,it will enter iterate,and it will output the result.(3)Run the algorithm program from the collated raw data.The results calculated by the algorithm are compared with the measured values,and the possible causes of error are analyzed.This article proposes a ground-based control point triangulation method based on GNSS PPK technology,after processing the GNSS antenna center coordinates as control points,using the algorithm to achieve aerial triangulation without ground control points,the outer orientation elements of each photo on the route and the ground coordinates of the same name on the photo are solved.No ground control point and no IMU are required.The result proves that this algorithm has high computational efficiency.The measurement technology has great significance for actual production.