基于航空摄影测量的填埋堆体动态重构精度及影响因素

填埋堆体表面形变监测是填埋场库容管理和堆体失稳等风险分析的核心,其时空高分辨率监测研究近年来引起广泛关注。基于航空摄影的地表测量技术具有采集速度快、时空分辨率高等优点,但在填埋场特殊环境下,面对高频填埋活动、显著的堆体变化以及防雨膜覆盖等干扰时,要同时满足高时空分辨率和耗时短的动态监测要求,无人机的最佳飞行参数设定亟待研究。为此,该研究模拟中等规模危险废物填埋场的规模和日填埋量,利用专业级无人机获取模拟区域图像,空三加密处理生成三维点云数据,利用Arcmap叠加分析多期监测数据,从点位坐标、重构尺度、重构体积、体积差分精度4个角度分析重构误差。结果表明:三维重构的坐标精度可以达到米级;重构尺度误差为2~3 cm,重构体积误差为0.16~0.17 m³,差分体积误差为0.16~0.17 m³;进一步研究发现,高度为25~55 m时,高度越高精度越低,相机倾角为-53°,-60°]时,精度最高,旁向重叠率大于80%时,误差骤减且基本稳定。考虑到填埋场的填埋作业间隔、无人机续航能力等对飞行时间的约束,为获得最佳精度,建议无人机飞行高度为37 m、相机倾斜角度为-53°,-60°]、旁向重叠率为80%。

Accuracy and Influencing Factors of Landfill Dynamic Reconstruction Based on Aerial Photogrammetry

Surface deformation monitoring of landfill is the core of landfill capacity management and risk analysis such as heap instability, and research on high spatial-temporal resolution monitoring has attracted much attention in recent years. The advantages of surface survey technology based on aerial photography are fast collection speed and high spatial and temporal resolution. However,the operating environment of landfill is special and complex. Faced with the requirements of large dynamic amplitude,high frequency, rapid comprehensive monitoring, and the presence of interference such as high-density polyethylene geomembrane coverage, obviously, it is necessary to meet the conditions of high spatial-temporal resolution and short time consumption at the same time. The urgent need to investigate the optimal flight parameters must be addressed. The scale and daily landfill of medium-sized hazardous waste landfill were used as simulation objects,and images of the simulation area were collected by professional unmanned aerial vehicle. The point cloud data is generated by processing the image data through space triangulation encryption,and the monitoring data of multiple periods are superposed and analyzed by Arcmap. The reconstruction accuracy is analyzed from four perspectives:point coordinate,reconstructed scale,reconstructed volume,and volume difference. The results show that the accuracy of the reconstructed point coordinates can reach meter level. The accuracy of scale measurement can reach 2-3 cm, the volume error is 0. 16-0.17 m³, and the difference volume error is 0. 16-0.17 m³. Further research shows that the higher the altitude within 25-55m, the higher the precision. The camera inclination has the highest accuracy when the tilt angle is -53 degrees, -60 degrees]. When the overlap rate is greater than 80%, the error decreases sharply and remains basically stable. Considering the constraints of landfill operation time interval and unmanned aerial vehicle endurance on flight time,it is recommended to select 37m flight height,camera tilt angle of -53 degrees, -60 degrees], and lateral overlap rate of 80% to ensure the best accuracy under flight time constraints.