# Extended Reality: Types and Applications
## 3 Applications of Extended Reality
### Extended Reality and Its Usage
#### 3.1.2 Augmented Reality and Its Usage  
Augmented reality technology provides visualization of objects that overlay on the real world. The real environment is captured by the camera, and its position is tracked using sensors [34]. The computer system analyzes the images of the real world, adds the virtual object to the image, and shows the result on the screen of the computer, phone, or HMD headset. Additionally, modern HMD headsets can track hand and leg gestures to increase the usability of the AR interface [43]. Below in the text, typical examples of AR applications in various fields are given. * Education--AR can improve the quality of learning by showing more information in an interactive way than a regular book can provide. Some books or magazines may have special markers printed on them. By installing an app on your phone, you can see more information or \"bring to life\" the book with animated visualization. In school education, this technology can improve academic performance and make students more interested in learning a subject by explaining complex material in an engaging and interactive way [44]. * Navigation and Tourism--AR is gradually being introduced for navigation, such as the previously described projection display that helps with navigation, thanks to the leading AR systems Google ARCore, which make it relatively easy to create applications with augmented reality, ensuring the emergence of new applications. Based on this system, the Google Maps application has an AR navigation mode. As with projection displays, Google Maps also shows the direction of travel, but with the visualization tied to the first world. This makes navigation as clear as possible. * Medicine--It became efficient in surgery, especially ultrasound-guided interventions. This allows doctors to learn faster and reduces cognitive load, thereby making their work easier [45]. The surgery preparation procedure also could be simplified using detailed 3D visualizations of all the patient's anatomical features [23] or the use of a projector to visualize the internal operation process on top of the body [46], as shown in Figure 3. AR could also be used for direct robotic system control, remote surgery processes, or studying [47]. * Assistance--Using an AR assistance system (Figure 4), non-qualified workers can complete the task while a qualified specialist is not on-site, for example, while on vacation or sick leave. Specialists or service help can provide AR instructions, like \"go here\", \"open this door\", \"press that button\", and \"enter these commands\". This helps in machine maintenance or fast problem solving [38]. Figure 3: AR visualization of an internal operation process on top of body [46]. (**a**) Visualization of a transparent body phantom in ARssist. (**b,c**) Examples of AR-based visualization of endoscopy in ARssist. Manufacturing Planning and Maintenance--During the planning of a factory floor, augmented reality can visualize how an empty room will look with installed equipment to check how it fits and determine if it will be comfortable to use. Augmented reality is used with a tablet camera and integrated lidar for tracking a mobile robot's position for planning and visual simulation of the routes of mobile robots or work of other equipment [48]. AR helps to see a virtual robot in conditions that are close to reality (Figure 2). Also, it is useful for technical support for quick problem solving. Modern usage of XR is a collaboration between robots and humans [38]. Furthermore, in manufacturing, AR can be used to help employees understand new tasks easier and faster by showing virtual schemes or instructions of a task that overlay on a real world [39]. The maintenance help system shows the lifetime of equipment or provides necessary reparation plan for personnel, using predictive fault finding (Figure 5) [49]. Figure 4: Operative assistance as well as manufacturing planning and maintenance using augmented reality [39]. (**a**) Pick-by-vision with HMD AR glasses. (**b**) Context-aware HMD AR-assisted maintenance.