Analysis On Low Altitude Uav Aerial Triangulation Accuracy

Low altitude UAV photogrammetry exist its own defects,which determine remote-sensing image has some problems, such as len distortion, angle of curl is big, operation picture format is too much, too small or overlap degree and UAV itself system hardware,etc.These problems perplex from UAV shooting to later period data processing.For these problems, this article will start from algorithm, studying the possibility of solving the problem. For those can’t be solved through algorithm, to check if can be reverse calculated. All of these studying problems launch around aerial triangulation content of Low altitude UAV Photogrammetry.This article surrounds UAV aerial data as a study object,discuss hardware requirements of low altitude UAV,the characteristics of photographic data,distortion correction,image matching and bundle adjustment process, analyse various issues which influence Aerial triangulation encryption results and solutions.This article discusses below several aspects:(1)As low altitude UAV task is aerial work, this article discusses the relationship between height, speed and length of exposure of its platform, and briefly introduces the technology of photogrammetry and demand orientation.(2)As the digital camera is a non-metric lenses, it is easy to produce optical distortion error, which requires to use distortion correction model. But error value is too large after image correction,so image correcting is necessary before the aerial triangulation encryption,which determine the later mapping accuracy.(3)Due to various reasons during Low altitude UAV flying, remote sensing image exsits Heading overlap and side overlap irregular, rotation angle is too large,etc issues. This case requires to use matching technology,however, the gray matching is difficult to meet the current precision requirements.The article introduce a kind of current popular matching technology,which based on the matching test of Harris algorithm and SIFT algorithm, and has very good stability in allusion to various appeared problems.(4)On the basis of bundle adjustment, the article introduce the adjustment way,and discuss traditional, modern aerial triangulation process. It briefly introduce the analysis method of accuracy of aerial triangulation, reveal the propagation formula of theoretical error and the model of actual accuracy value, also combine with the national standard and give different scale accuracy limits.(5)Accuracy is an important indicator of aerial triangulation, understanding all links reflects the quality of Photogrammetry directly. As aerial triangulation links are too many,in order to ensure the precision of final result, accuracy analysis must be carried out in every aspect to get better result. In this article, it designs the influence of different threshold and different control points on more precision, surrounds finding the way of adjustment to draw the wrong test and coarse reject poor match point,comparing analysis thresholds and control point adjustment precision value.