Research For IMU/DGPS-supported Airborne Photogrammetry Practice

Airborne Photogrammetry is an important method to obtain the spatial geographic information, which plays an important role in the national economy, and the main production methods of basic topographic map in our country. Traditional photogrammetry process is cumbersome, workload is big, which needs to spend a lot of manpower and material resources, also the production efficiency is very low, this restricts the construction of the spatial geographic information framework in our country. With its high efficiency and easy to implement features, Developed IMU/DGPS-supported Airborne photogrammetry gradually becomes the main production method of Airborne Photogrammetry in recent years.IMU/DGPS-supported airborne photogrammetry avoids the traditional photogrammetry which needs to deploy a large number of control points to do aerial triangulation practices. Using combination of IMU/DGPS system captures images of exterior orientation elements directly, again by a small amount of control points adjustment calculation, the accuracy of the exterior orientation elements obtained can be further improved, greatly reducing the workload for deploying the control points in field layout. For some hard to reach difficult areas, it will also be able to carry out mapping work, and can achieve rapid mapping, production various types of digital map products. Therefore, IMU/DGPS-supported photogrammetry can meet the needs of geospatial information update quickly, has very expansive development prospects.Based on the basic principles of previous scholars, this paper studies the basic principle of inertial navigation system and differential GPS respectively, discusses the advantage of combination of IMU/DGPS system and the merits of combination method. Then the paper studies the principle of IMU/DGPS-assisted aerotriangulation, key techniques and error sources, analyzed the work methods and processes by using the IMU/DGPS-assisted aerotriangulation method production digital orthophoto map, combined with the actual production project, make a validation about the results accuracy as well as the feasibility of IMU/DGPS-assisted aerotriangulation.The main content of the paper: 1) Study the principle of combination of IMU/DGPS system, analysis the advantage of combination of IMU/DGPS system and error sources.2) Study the two ways of IMU/DGPS-supported Airborne Photogrammetry:Direct georeferencing and IMU/DGPS-supported aerial triangulation, and analyzes its key technology.3) study the production methods and processes of aviation digital orthophoto map, focuses on the two algorithm of aerial digital images ortho rectification:based on the directly correction method and indirect correction method of collinearity equation model of aviation digital images.4) Combined with instance to implement the IMU/DGPS-supported Airborne photogrammetry, study the POS data decoding method and IMU/DGPS-assisted aerotriangulation production digital orthophoto map method, analysis imaging accuracy of exterior orientation elements and the quality of digital orthophoto map through several schemes, summarizes the work process and applicable scope of the IMU/DGPS-assisted aerotriangulation.