###### Abstract  
Remote collaboration for construction site management is challenging. Building Information Modeling (BIM) provides the potential for remote collaboration based on its powerful data compatibility. Furthermore, the recently evolving Mixed Reality technology improves visual perception by superimposing 3D virtual BIM objects on real-world artifacts. This study proposes a remote collaboration system based on BIM in Mixed Reality. This system consists of three-unit systems: (1) Field Operator System (FOS), (2) Communication Server, and (3) Office Manager System (OMS). FOS was developed based on MR smart glasses for a field operator. The field operator can manipulate virtual BIM objects with finger-pointing cues and share the view with an office manager. FOS creates Mixed Reality Capture (MRC) video, the combined image of real-world images of existing artifacts in the construction site with virtual BIM elements superimposed on them, and sends it through the Communication Server to OMS. Thus, the office manager can see the field operator's view through OMS based on a desktop or tablet PC. The office manager can give instructions to a field operator by voice through OMS. A user test was conducted to evaluate the applicability of the developed prototype system. As a result of the test, it was found that most of the testers had a positive evaluation of the developed system. This paper discusses the development of the BIM and MR-based remote collaboration and the test results. remote collaboration; Mixed Reality; Building Information Modeling; head-mounted display +
Footnote †: journal: Medical Imaging  
1
Footnote 1: email: _Applied_  
20 July 2022  
Accepted: 27 August 2022  
Submitted: 31 August 2022  
the AEC industry. As a result, communication among participants from different divisions was limited, and data compatibility was not guaranteed. BIM also gives us on-monitor 3D models but does not meet the demand for scaling to real-world scales [5]. Extended reality (XR) technology provides a solution to overcome these limitations of BIM. XR is a generic term for immersive technologies, including virtual reality (VR), augmented reality (AR), and Mixed Reality (MR) technologies. According to the degree of experience that blurs the boundary between the real and virtual world, it is classified into VR, AR, and MR. This study focuses on MR, where physical and digital objects are presented together, which has tremendous potential to improve AEC efficiency and productivity [6]. MR-based design reviews can effectively communicate information to the client compared with 2D media. This study challenges to increase communication effectiveness and efficiency between a field operator and office manager on a construction site by employing BIM and MR. As mentioned above, higher productivity improvement can be expected through effective remote collaboration on a construction site. Since experts from various fields, such as structural engineers, constructors, electrical engineers, and mechanical engineers, work together for a construction project, it is important to communicate properly among them. This is because, in many cases, it is difficult to understand the other person, no matter how well they express it in words. In other words, if the field operator sees the artifacts of the site and the BIM object to be checked by the office manager are displayed on the same display simultaneously, communication efficiency will be greatly increased. This study aims to develop an MR-based remote collaboration system that can interactively move BIM objects. This system works in the Internet environment and supports communication between field managers and office managers. This system allows the office manager to see the field operator's view with the virtual BIM objects superimposed on it. The field operator can also move BIM objects around with finger-pointing cues. Through this, the communication effectiveness and efficiency of the two collaborators can be improved.