## 1 Introduction  
The construction industry has been recognized as a dangerous and hazardous industry throughout the world [1, 2]. Despite providing a significant contribution to a country's development, construction accidents have accounted for a very high rate among various industries [3]. For instance, safety statistics reveal that construction accounts for 20-40 percent of the occupational fatal accidents in spite of employing just around 6-10 percent of the workforce. Throughout the world, approximately 60,000 construction fatalities occur per year, which corresponds to one injury every nine minutes [4]. Consequently, fatalities and injuries cause many cost overruns and delays, which negatively impact the project safety performance [5]. To reduce construction accidents at the workplace, it is very important to provide graduates with hazard education at the tertiary level, so that they have professional hazard knowledge and skills [6; 7]. In the past decades, virtual reality has been acknowledged as a state-of-the-art technology to improve hazard education [8]. The 3D CAD models are developed using computer to provide a 3D virtual reality (3D-VR) platform [9]. The advantage of 3D-VR is that it provides virtual construction sites, where students can interact with the educator and other learners to obtain hazard knowledge and skills [10]. With an interactive learning environment, learners will be motivated and engage sufficiently with their construction hazard investigation and recognition [11]. Moreover, recent efforts [12] have developed 3D-VR based object anatomization models for anatomizing and analyzing complicated hazard case studies. This object anatomization approach has benefits not only in construction hazard education [12] but also in other disciplines [13; 14; 15]. Despite its advantages, 3D-VR lacks a real-word environment [16], in which graduates can experience practical construction sites to investigate hazards. To improve the real-world experience, 360 degree panoramic Virtual Photoreality (360 VP) has emerged as a potential pedagogic tool for learners to experience real-word construction workplace environments [17]. The advantage of 360 VP is that it provides an immersive learning platform, where the learner can move flexibly and observe the scenes to investigate hazards as they would experience in real construction sites [18]. Due to the greater immersion and higher degree of realism, 360 VP assists learners in experiencing an emotional and cognitive presence at the scene. Moreover, the 360 VP platform has been proved to be energy-efficient [19] and cost-efficient compared to the 3D-VR [20]. Despite the prominent advantages, the current applications of 360 VP still lack 3D object anatomization tool to enhance the learning outcomes. Moreover, in recent years, researchers have focused on adapting virtual reality technologies separately, and lack of research integrates 360 VP with 3D-VR to eliminate limitations and maximize the advantages of these technologies for promoting educational purposes. In response to this status-quo, this research proposes a construction hazard investigation system, which leverages 3D object anatomization on an Interactive Augmented Photoreality (iAPR) platform. The proposed iAPR system augments a 360 VP platform by integrating 3D-VR object anatomization technologies in order to create a learning environment, which reflects a real-word construction workplace. The iAPR consists of three key learning modules including Hazard Understanding Module (HUM), Hazard Recognition Module (HRM), and Safety Performance Module (SPM), which adapt [PERSON]'s taxonomy learning theory for hazard investigation knowledge and skill development of learners. A prototype is developed with hazard cases that often occur in real construction workplaces. In addition, the effectiveness of iAPR in improving the hazard investigation is validated using before-after experimental studies.