# End-Users' Augmented Reality Utilization for Architectural Design Review
## 1 Introduction  
Architectural design is a continuous process of meeting a client's needs through collaboration [1]. As acquiring reliable feedback from end-users for the assessment of design options would be beneficial for the overall quality of the design and end-user satisfaction, the design review process involves not only designers and engineers but also end-users [2, 3]. Design review with end-users also requires a continuous iterative process of sharing building information, and the client is generally provided with project-relevant information by the design team in the form of drawings or models. During this information sharing, finely visualized building information could improve the understanding of design concepts and ideas and facilitate the effectiveness of communication between participants [4]. To support information delivery and management, building information modeling (BIM) is rapidly being adopted by project participants. Moreover, three-dimensional (3D) models allow non-technical parties to understand designs more quickly compared to 2D drawings [5]. 3D models have mostly been presented through 2D systems so far. That said, the recent use of virtual reality (VR) and augmented reality (AR) technologies are gaining considerable attention as a new means of visualization platform. Immersive VR environments using a cave automatic virtual environment (CAVE) or a head-mounted display (HMD) have also been widely used for design review [6]. Recently, with the introduction of a new AR system called HoloLens by Microsoft, an AR system that superimposes a virtual model in thereal world has shown its potential as an alternative visualization platform in various applications such as construction simulation and clash detection [7, 8]. With a head-mounted device (e.g., HoloLens), users can get a more realistic visualization in a physical environment, which increases the sense of presence and immersion for users. Applying AR to building design tasks allows users to get a more realistic visualization of a 3D building in the real world, which is not easily achieved with traditional or VR-based methods. However, despite the potential of AR as a new visualization platform, the application of AR for design collaboration remains a niche area. In fact, most efforts in previous studies have focused on the technical development of AR systems, such as the real-time registration of virtual objects into real-world scenes [9]. Limited attention has been paid to investigating how useful the new AR system is as a visualization tool for design review from an end-user's perspective [10]. Therefore, project participants are still not familiar with the use of AR technology for design collaboration; as such, it is difficult to choose an appropriate visualization platform that enables end-users to better understand building information during design review. To facilitate the use of the AR system for design review, it is necessary to ensure that the perception of AR-based design information can improve the end-user's level of awareness to building information, and will improve the user's experience for design review tasks. However, few studies have investigated the user's comprehension of building information and the mechanism of AR experience on user-involved design review activities. With this research gap, this study aims to investigate the visual presentation quality and user acceptability of an architectural design presented using AR through a controlled experiment. In particular, the experiment was designed to compare design review effectiveness and user perception between AR and other existing visualization platforms (i.e., visualization using a 2D monitor and a VR system). For the experiment, 76 undergraduate students were recruited and provided with different design alternatives using three types of visualization platforms (i.e., 2D monitor, VR, and AR) to test the feasibility of the new technology under the perspective of a general user.