Research On UAV Oblique Photogrammetry Modeling And 3D Model Visualization

With the rapid development of UAV technology,oblique photogrammetry using consumer-grade UAV has become an important method of data acquisition and is gradually maturing and production applications,while visualization and spatial measurement analysis of 3D results of oblique photogrammetry have become more urgent.As the most popular open source 3D GIS framework,Cesium can display virtual earth directly on browser and display multiple layer elements,which provides a good platform for visualization and application analysis of oblique photogrammetry data.This paper focuses on the oblique photogrammetry and model data visualization of consumer drones,we discuss the key technology in the single-lens oblique photogrammetry modeling process,such as camera calibration and bundle adjustment.Based on Cesium,we realize the visualization and 3D measurement and analysis functions of oblique photogrammetry data.The main research results are as follows:(1)Based on the detailed discussion of the key technologies of calibration,image feature extraction and matching,bundle adjustment and dense matching of non-measurement cameras,Two schemes of simulating multi-lens oblique photogrammetry with single-lens UAV are we proposed,namely,one is simulating three-lens oblique photogrammetry with three flight routes and the other is simulating five-lens oblique photogrammetry with five flight routes.The accuracy of the two schemes are evaluated by the error of the checkpoint.The results show that the second scheme is more accurate than the first scheme.From the aspects of flight efficiency,data processing speed and data product accuracy,this paper gives suggestions for adopting two schemes for different terrain and feature distribution,which provides a reference for actual production.(2)This paper deeply analysises the 3D model data format of 3D Tiles dataset and the conversion of existing OSGB data format to 3D Tiles format;For the huge volume of 3D model data in oblique photogrammetry,scene clipping algorithm and data loading scheduling method based on multi-fork tree are proposed,which improves the rendering efficiency of Cesium 3D model data visualization and achieves different levels.(3)A Cesium-based oblique photogrammetric 2D and 3D data visualization and spatial measurement module is designed and implemented.The module is based on B/S architecture and contains two parts.On the one hand,the module can present the 3D data of oblique photogrammetry perfectly.On the other hand,it can measure and analyze the data in typical space.The measurement functions include coordinate pickup,distance measurement and area measurement.Typical spatial analysis functions include slope and aspect analysis,profile analysis,submergence analysis,excavation and filling calculation,visual analysis and horizon analysis.