Augmented-Reality Survey: from Concept to Application <s> Training & Education <s> Augmented reality involves the use of models and their associated renderings to supplement information in a real scene. In order for this information to be relevant or meaningful, the models must be positioned and displayed in such a way that they align with their corresponding real objects. For practical reasons this alignment cannot be known a priori, and cannot be hard-wired into a system. Instead a simple, reliable alignment or calibration process is performed so that computer models can be accurately registered with their real-life counterparts. We describe the design and implementation of such a process and we show how it can be used to create convincing interactions between real and virtual objects. <s> BIB001 </s> Augmented-Reality Survey: from Concept to Application <s> Training & Education <s> Construct3D is a three-dimensional geometric construction tool specifically designed for mathematics and geometry education. It is based on the mobile collaborative augmented reality system "Studierstube." We describe our efforts in developing a system for the improvement of spatial abilities and maximization of transfer of learning. In order to support various teacher-student interaction scenarios we implemented flexible methods for context and user dependent rendering of parts of the construction. Together with hybrid hardware setups they allow the use of Construct3D in today's classrooms and provide a test bed for future evaluations. Means of application and integration in mathematics and geometry education at the high school, as well as the university, level are being discussed. Anecdotal evidence supports our claim that Construct3D is easy to learn, encourages experimentation with geometric constructions, and improves spatial skills. <s> BIB002
AR technology has been applied to assist soldiers in the repairing of their weapons or their machines on the battlefield, or for training purposes with wearable-device accompaniments. An AR system can warn soldiers about the potential dangers around them, and it can support virtual maps to help the moving direction of a soldier. The system can also project realistic training scenarios, including virtual tanks or helicopters, into their field of vision regardless of their physical location. Surgical training, for which exercises of routine or complex operation procedures are undertaken, is essential for the enhancement of the surgical operation skills of trainee surgeons. Because AR surgical training is both time and cost intensive, it has been applied in the form of a superimposition of computer generated virtual organs in the trainee-surgeon vision field with the use of an optical HMD such as Google Glass or the STAR 1200 XL from Vuzix [83] . The holographic displays such as the Microsoft Hololens  or the Google Magic Leap [85] can localize tumors in the trainee-surgeon view and highlight specific anatomical features to help the instructors in their guidance of the trainees. For new manufacturing workers, the work-preparation process is difficult without a familiarity regarding the corresponding tools. AR training provides a direct or indirect view of a physical real-world environment like a factory, and the elements are augmented by computer-generated objects. A number of AR-based manufacturing applications have been developed such as a laser-printer maintenance  , an object calibration BIB001 , and automotive and aerospace maintenances. The Hyundai motor group introduced a virtual guide  that is an interactive owner's manual for which AR is used to show the components of the dashboard and the engine area, whereby the user can be intuitively guided to fix minor car-repair issues. The AR-teaching and AR-learning approaches have been intensively studied by educational and computer-science researchers. Textbooks, flashcards, and other educational materials can contain AR-technology-based supplementary information, whereby students can readily understand the detailed concepts of physics, anatomy, astronomy, mathematics, and geometry through the corresponding interactive play BIB002 . The AR Flashcards [90] can be used to help students learn and understand the core concepts of the alphabet, color and shapes, and space with AR technology. For Anatomy 4D [91] , AR is used to present the human body, and students can learn about the different systems and the human anatomy. The Elements 4D [92] inspires students to explore chemistry, from the elements to life, in an immersive and interactive manner. For the Arloon Geometry  , AR is used to present 3D models of most of the geometric shapes that students can directly interact with them. SkyView [94] is an intuitive stargazing application for which the user's smartphone camera is used for the identification of the stars, constellations, and satellites in the sky. Fig. 2 shows snapshots of these AR-based training and education applications. 