免像控无人机高清倾斜摄影三维建模精度分析

Precision Analysis of 3D Modeling by High Resolution UAV Oblique Photogrammetry with No Control Point

对于大落差山区,常规无人机倾斜摄影测量往往难以顾及山脚等重点关注区域,为达到测图精度并将模型转换为工程所需坐标系,通常需要布设大量可靠的外业像控点,然而,在地灾体上人工布设测量像控点的难度极大。结合西南山区某铁路山体滑坡抢险项目的内外业工作,利用Phantom4 RTK无人机在不同航高、不同角度进行免像控模拟倾斜摄影,通过航线优化设计及对曝光点进行坐标转换,完成重点关注区域的高精度模型三维重建。研究表明,相较于传统无人机倾斜摄影,新方法可减少1/3的内外业工作,精度可达到1∶1 000比例的三维模型精度要求。

For the mountain areas with huge height difference, traditional UAV oblique photography assembled with multiple cameras is often difficult to take into account key areas such as the foot of the mountain. In order to achieve the accuracy of surveying and transform the model into the coordinate system required by the project, it is necessary to lay a large number of reliable field image control points.Nevertheless,traditional method is not applicable to geological hazard areas since high risk of the plotting work. Based a landslide rescue in the southwest mountainous area,Phantom 4 RTK is adopted to capture oblique photographs with several different angles with different flight heights and no control points. 3D mesh modeling of the mountain areas with detailed focus on landslide areas are built and the positions of these photographs have been transformed to the engineering independent coordinate system. The Results show that,when comparing with the traditional method,applying Phantom 4 RTK system to imitate oblique photography is more efficient by reducing 1/3 of the field workload and its accuracy meets with requirements for 3D model with a scale of 1∶1 000.