Applications of 4D Point Clouds (4DPC) in Digital Twin Construction: A SWOT Analysis

Digital twin construction (DTC), the virtual replica of physical construction, is an essential enabler for the promised Construction 4.0. Thanks to its real-time virtual-physical synchronicity, many uncertainty-tolerant functions, and applications, such as system integration, testing, monitoring, and maintenance, could be dynamically simulated and optimized through the DTC. The data foundation for creating or updating a DTC is real-time reality capture on construction sites. Despite a lot of efforts such as the Internet of Things (IoT) and AI cameras, so far, it is very challenging to capture the spatial-temporal information of the whole construction site. Time-dynamic 4D point cloud (4DPC) is an emerging sensing technology consisting of three-dimensional point cloud scans at a frequency, e.g., two frames per second. 4DPC has been successfully used in several industries, such as autonomous driving and motion analysis in sports science, due to its ability to capture dynamic objects and environments. This paper presents a strengths, weaknesses, opportunities, and threats (SWOT) analysis of the possible applications of 4DPC in DTC. In summary, 4DPC can effectively capture the dynamic feature of construction progress, with strengths in real-time information updating, covering more precise geometry dynamics, and providing localization and mapping information, etc., which are in line with the development of DTC. Meanwhile, the disadvantages include errors or noise in recognizing lign-permeable materials and water, enormous data volume, challenges in modeling spatial-temporal structure, and computation load in processing. The 4DPC receives several opportunities, such as establishing a dynamic data foundation for construction automation and modeling of workspace and integrating with 4D BIM for creating DTC; However, threats such as LiDAR-hostile weather and emerging competitors are also identified. Overall, 4DPC is a promising research direction that may interest DTC researchers and practitioners for various application situations in the construction industry.