控制点布设方案对无人机精度测量的影响及其应用

近年来矿区地质灾害愈发严重。为准确监测尾矿坝地表沉陷变形，以地形地貌复杂的尾矿坝为研究实例，开展无人机低空摄影的形式进行监测数据收集。无人机原始POS数据存在系统误差的问题，文章利用误差改正模型纠正原始POS数据，并设计7种像控点布设方案，并对获取的尾矿坝高分辨率正射影像及DEM进行了精度评价。结果显示，当布设像控点数量为8个时，数据误差可以控制在3 mm以内；用两期DEM数据差值覆于地面模型，生成尾矿坝沉降图, 沿Y=350 m、Y=100 m和X=60 m剖面线做剖面图。基于测量结果发现，尾矿坝已出现整体沉降，其中南部尾矿坝下坡沉降范围最大，沉降范围在0.16 m之内。这次应用验证了在尾矿坝地表监测中无人机低空摄影测量的精度是可靠的。利用无人机的高精度成图方法对尾矿坝变形进行监测，对应急响应溃坝可能导致的绿洲地区及周边河湖生态灾难地形和矿区安全生产起到一定的预警作用。

Influence of control point number on UAV low-altitude photogrammetry and its application: A case study in subsidence monitoring of a tailing dam area in northwestern China

Geological disasters in mining areas have become more and more serious in recent years. For accurate monitoring of surface subsidence with complex topography of tailings dam, based on the monitoring data of UAV(Unmanned Aerial Vehicle) low-altitude photogrammetry, the UAV original POS(Position and Orientation System) data error were improved, data from the error correction model was used to correct the original POS model and 7 kinds of control point layout were designed, high resolution evaluation was conducted on the orthogonal projection as well as the DEM(Digital Elevation Model) accuracy. The results show that when the number of image control points is 8, the data error can be controlled within 3 mm. The settlement map of the mining dam is generated by overlaying the ground model with the difference values of the two DEM data, and the profiles with Y=350 m, Y=100 m and X=60 m were made respectively. The measurement results indicated that the tailing dam has been subsided as a whole, and the southern mining dam has the largest subsidence area, which is within 0.16 m. This application verifies that the accuracy of UAV low altitude photogrammetry in mining dam surface monitoring is reliable. The high-precision mapping method of UAV is used to monitor the deformation of tailing dam, which plays a certain early warning role in the ecological disaster terrain of the oasis area and the surrounding rivers and lakes which may be caused by the emergency response of dam break and the safe production of mining area.