土方量測算技術之運用及比較

Application and Comparison of the Measurments for Earthwork Volume

本研究以滯洪池為案例，分別採用GNSS（Global Navigation Satellite System）即時動態定位、地面光達掃描以及UAV（Unmanned Aerial Vehicle）空拍測圖等不同技術，透過空間量測先行獲取工程體之點雲資料，再運用空間製圖軟體組成三維模型，進而完成工程體之土方量解算。由研究成果發現，UAV航拍測圖（配合地控點使用）之成果，與地面光達掃描獲取之土方量差異僅有0.1%。而運用GNSS即時動態定位之測算成果，則會因其採樣點間距較大，而與UAV測圖成果出現約18.8%之較大差異。此外，為求UAV外業更加快速而不使用地控點時，其土方測算成果會相差1.2%；另為求UAV建模更加快速而將航測相片數量減少一半時，其土方測算成果之差異僅約0.6%，但資料解算時間可大幅減少2/3，相關之簡化作法當可作為災害現場快速測算土方量案例之運用參考。

A flood-storage pond was selected and adopted as a case study for this paper. Different measuring techniques such as GNSS real-time kinematic (RTK) positioning, terrestrial LiDAR scanning and UAV photogrammetric mapping were used to first obtain the point cloud data of the engineering body, and then operated the spatial mapping software to construct three-dimensional model. The calculation of the earthwork volume was finally completed for the engineering body. It has been found from the tests that the result of the UAV aerial mapping, in conjunction with the ground control points, is only 0.1% different from the volume obtained by the terrestrial LiDAR scanning. The results using GNSS RTK are greatly different from the UAV mapping results by 18.8% due to the large sampling interval. In order to make the UAV operation faster and easier by not using the ground control points, the volume calculation results are differed by 1.2%. To pursue UAV modeling more rapid, the number of aerial photos are tried to be reduced by half. The difference between the calculation results is only 0.6%, but the data resolving time can be greatly reduced by 2/3. The related simplified methods for UAV modeling can be taken as a reference for the rapid calculation of earthwork volume on the disaster site.