Structure-From-Motion for Earthwork Planning

The reconstruction of surfaces from unorganized point clouds can be of great use in construction applications. Point clouds are mostly created by 3D scanners. Another technique for generating point clouds is the structure-from-motion technique, where the point cloud is generated from a sequence of images. This paper utilizes a surface reconstruction technique to model and quantify earthwork. The described technique can be used in preliminary planning, for project updates, estimating of earthwork quantities, as well as for embedded planning systems in construction equipment. The paper examines the use of structure-from-motion techniques in earthwork application and identifies limitations and, pros, and cons of this approach. Data from 23 earthwork excavation construction sites were collected and analyzed. 3D surface reconstructions were applied on the 23 sites during the construction phases and 3D surfaces were reconstructed and compared to the original land form. In addition, similar experiments were conducted with piles of earth. The results were analyzed to determine appropriate ranges of use for structure-from-motion surface reconstructions in earthwork applications. Results show that the technique is most suited for pit excavations with areas less than 2000 meter squared and with depths up to 5 meters. In addition, piles up to 10 meter highs and with base areas up to 300 meters were successfully reconstructed. The results of this paper should be of great importance to contractors willing to utilize this technology in everyday use.