## 1 Introduction  
Modular construction is the process where projects consist of individual sections, prefabricated in an off-site controlled manufacturing facility, and assembled at the construction site. This method can overcome the influence of factors such as poor construction site environment on the project quality. The quality control of modular construction is mainly carried out from three aspects: preconstruction stage, production stage, and installation construction [1]. Modular construction effectively improvesthe efficiency and quality of both design and construction. Also, it shortens the duration and cost of construction projects, which represents an important trend in the development of architectural industrialization [2; 3; 4]. A floodwall is a primarily vertical artificial barrier that is erected along the banks of a stream or path of floodwaters to prevent floodwaters from reaching the area behind the structure during seasonal or extreme weather events. Traditional floodwalls are mainly constructed from concrete and metal elements. This system requires a large land area, which may restrict access to the structure. It can be costly for construction and maintenance. Also, the traditional floodwalls may block the natural view and damage the landscape along the river. Hence, a removable floodwall system is designed and introduced to overcome those challenges brought by the traditional floodwalls. Unlike traditional ones, these structures are movable and can be deployed or erected only in flooding times. Removable floodwall systems can be applied to individual buildings, smaller areas, or a large scale of the infrastructure such as dams, large-size port piers, railway tunnel portals, culvert openings of expressways, openings of civil air defense structures, and urban large-scale communities to prevent flood disasters [5]. Compared with traditional flood protection methods, the removable floodwall takes advantage of the low labor intensity, high work efficiency, and small seepage [6]. Also, a removable floodwall gives protection in case of flooding and open access to the floodplain over the remaining time. It can also be used as an emergency tool against flooding in unprotected low-lying areas in addition to the heightening of permanent flood protection structures in extreme events. The installation processes of removable floodwalls typically consist of two permanent installed components (end posts, anchor plates) and four removable components (logs, ground seal, pressing tool, center post). Reinforced concrete plinths embedded with anchor plates are constructed in advance at the site of floodwalls. The center posts are bolted onto the stationary anchor plates. The logs are then compressed vertically with the pressing tools to provide a high level of leak tightness. The logs will get compacted among themselves because of their intermediate seals. Additionally, the lowest log with its special ground seal creates a water-tight seal with the ground. After the flood recedes, all components are reversely removed and orderly stored in a warehouse. One of the critical installation procedures is the accuracy tolerance control of anchor plates, embedded in reinforced concrete plinths for connecting fixed columns. Ensuring the installation precision of anchor plates without deviation during concrete pouring is crucial because the control precision of concrete pouring is in millimeter accuracy. However, the current methods for analyzing anchor plates' tolerance accuracy rely primarily on manual inspections and contact type measurements, such as rulers and measurement tapes, which are time-consuming and costly. Also, there is a lack of systematic storage and management of the information obtained. A significant portion of the researchers and practitioners adopt non-contact sensing techniques to monitor the dimensional properties of the precast structures. Laser scanners have recently been one of the most popular measurement tools in the construction industry [7].