# The Integration of Earthwork Design Review and Planning Using UAV-Based Point Cloud and BIM
###### Abstract  
Earthwork is seemingly guesswork, but it requires a high level of accuracy and precise planning. Differences between earthwork design and finishing levels cause project delays and cost overrun due to the time-consuming nature of earthwork re-work. Therefore, error-free earthwork planning and design review is a key to the success of earthwork projects. This study utilized an integrated approach of an unmanned aerial vehicle (UAV)-based point cloud and BIM (Building Information Modeling) to verify the design and to operate the earthwork planning. The integrated approach was proposed and applied to a 420 square meters housing construction project to review an original earthwork design and create an earthwork plan for excavator work. As a result, errors in earthwork design that caused by inaccurate initial DEM was revealed, thus the earthwork design was revised with a UAV-based point cloud map. Additionally, the integrated approach was able to generate an explicit task sequence for an excavator. earthwork; point cloud; excavation; BIM; UAV; earthwork design +
Footnote †: journal: Medical Imaging  
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of the DEM are not good enough for centimeter-level of precision [3]. The 1:5000 scale is widely used for small housing projects during the initial design stage. The DEM is publicly available via ngini.gov.kr (National Geographic Information Institute of Korea), where DEMs are managed for public use. In this sense, surveying must be carried out repeatedly during earthwork construction to compensate for such inherent errors and faults in the DEM and earthwork design, and the frequent surveying interrupts ongoing tasks that impact the overall equipment productivity. Second, earthwork planning is also subjected to inefficient and heavily rely on the trial-and-error process. The earthwork planning method in practice is to generate equipment's working plan without excessive and unnecessary tasks. For example, the distance between cut and fill must remain the shortest as possible considering the moving costs and the accessibility of equipment and so on, and many studies on optimal excavation planning strategy have long been discussed, and have suggested that the use of BIM (Building Information Modeling) and 3-dimensional terrain bring about more accurate and robust construction planning [4; 5; 6]. To cope with such drawbacks in earthwork planning and design review, in recent years, there has been growing interest in the deploying of UAVs (unmanned aerial vehicles) in construction sites to rapidly and more precisely acquire terrain information by incorporating high precision RTK (Real-Time Kinematic) GNSS (Global Navigation Satellite System), photogrammetry, optical cameras and meta-data (e.g., focal length, field of view, etc.). The benefits of UAV-based terrain modeling have been well studied; not only the modeling time is very fast [5; 7], but the quality of the model in terms of position error is well maintained as compared to LiDAR, also known as the robotic total station (RTS). A UAV-based survey that includes 2D or 3D orthmosaic maps, 3D models, thermal map, photogrammetry, multispectral map, etc., that enable us to take a glimpse of construction progress at a rapid rate as compared to the traditional total station-based survey. At each stage of the construction process, high-resolution digital terrain models can be overlaid and compared with planned earthwork 3D design, and spatial discrepancies between plan and actual earthwork can be identified. As the UAV deployment may increase the accuracy and efficiency of earthwork design, what is unknown is the link between the earthwork design process and equipment. Although UAV-based design review may resolve the issue of design, the goal of earthwork construction for practitioners' perspectives is that they want to maximize their profit as they are adopting the new technologies.