Application of consumer drone in the earthwork estimation of artificial deposit in construction project

LIANG Shi;LIU Wanqing;WANG Ning;YU Lei;College of Urban and Environmental Science,Northwest University;Development and Service Center,Shaanxi Administration of Surveying,Map and Geoinformation;Xi'an Soil and Water Conservation Supervision Station;

consumer drone;;artificial deposit;;earthwork calculation;;measurement by oblique photography

[Background]In the monitoring of soil and water conservation in construction projects,there is a need to quickly and accurately measure the amount of earthwork in artificial deposits and to guide the reasonable disposal of earthwork,while the traditional measurement methods are difficult,costly and inefficient. To address these issues and explore the use of consumer drones to construct terrain models for rapid earthwork measurements,the accuracy and applicability of terrain models,which were constructed using conventional vertical down aerial photography and 45° oblique aerial photography to measure earthwork quantities at different schemes of control points,were studied and compared. [Methods]The authors used the consumer drone DJI Phantom 4 pro as an aerial photography platform to take aerial photographs of small deposits at the construction site of a construction project using two schemes,one was conventional vertical down looking single"Z"aerial photography and the other was simulated 45° oblique double "Z"cross aerial photography. The two aerial photography schemes were used to construct highprecision terrain models at different number of control points,and to measure the earthwork at the same bottom; meanwhile the RTK technique was used to collect ultra-dense feature points from small deposits and then construct terrain models to measure the earthwork. The amount of earthwork measured at this time can be considered as the accurate value of the earthwork. The difference between the amount of earthwork measured by the aerial photography method and the accurate value was calculated,and the ratio of this difference to the accurate value was used as the accuracy of the amount of earthwork measured by the aerial photography method. The measurement accuracy of earthwork quantities at different control point quantities under different aerial photography methods was analyzed. [Results]When there was no control point overall or at the top of the stack,the earthwork measurement error was < 3% for the oblique 45° double "Z"cross aerial photography. And the error was < 2% for the conventional vertical down looking single "Z"aerial photography,when there were five control points at the four corners and the deposit top. [Conclusions] The use of consumer drone aerial photography with a small number of control points to build a terrain model for measuring earthwork may meet the application requirements and accuracy requirements,and 45° oblique cross aerial photography is also highly accurate when there is no control point at the top of the deposit and thus can be widely used in the estimation of earthwork.