Research On The Technology Of Orthophoto Emergent And Expeditious Update

With the development of technology and algorithms of Remote Sensing andPhotogrammetry, the production and overall update for Orthophoto has made a great progress,however, there is still short of research and practice on the partial image updating,also somedemands are needed in some emergency surveying and mapping support tasks. To solve thisproblem and meet the actual demands of emergency surveying and mapping support, this paperstudies the theory and algorithms related to the technology of partial Orthophoto updating. Thekey points include feature extraction, feature matching and matching strategy, structuring thecorresponding triangular irregular network, updating of partial Orthophoto, acquiring thechecking points of the updating area and assessing the degree of accuracy etc.The main work and innovations of this paper are as follows:1. The paper analyses the reseach status for the related theory of the Orthophoto updatingtechnology and the demand situation for the partial Orthophoto updating. It also states theprinciple and algorithms of Orthophoto updating.2. In order to get the experimental result we expected, we selected a suitable algorithm offeature points false matching eliminating and improved it. We proposed a method that caneliminate the false matching points based on the connecting lines between corresponding points.This method is based on whether the lines linking the corresponding points cross with other linesor forms obvious intersection angle or not.A new method of multi-constraint false matchingeliminating is formed after combining with other algorithms,and the effectiveness of this methodis proved by experiment.3. The automatic update for the Orthophoto is realized based on the feature matching, theTriangulated Irregular Network and the Resampling Filter.4.This paper analyses and elaborates the theory about precision, which proposes a newmethod that evaluates the accuracy of updated partial image so as to test the practicality ofpartial Orthophoto updating technology. The new method uses the Feature Extract, the FeatureMatching and the Matching Strategy to extract the corresponding points from the updated area ofthe former Orthophoto and the new image, and then the accuracy of the updated image isassessed based on the features mentioned above and the mean square error of thesecorresponding points and control points.