# A Review on Augmented Reality in Education and Geography: State of the Art and Perspectives
## 2 Historic Overview of AR
The benefits of using the Google Glasses include that they are easy to wear and to use, they provide fast access to maps, chats and documents, such that there is no time lost searching them, and they show the information directly in front of the user's eyes, thus, the user can obtain their information faster. Nevertheless, there are also downsides to using Google Glasses. For example, the glasses are showing the information directly in front of the user's eyes, and so the information can mislead the user and may not include the environment near them. Also, one of the most important disadvantages is that the private data may be leaked and used in harmful ways. Since 2013, VR applications have started to be used more than ever in a considerable number of domains. First and foremost, the most approached field through VR is the gaming industry [5]. In this domain, the most important aspect for having the best quality time using VR is the immersive experience. The immersive experience refers to the perception of players in being part of a different environment than the real world and the feeling that they are present and engaged in that virtual world. This is achieved through a headset that is lighter than the HMD, which permits the player to move freely in the entire room where the headset is connected. Additionally, the player can move in the game by using two Direct Touch Hand Tracking devices, which can sense the movements and gestures of the player's hands with Infra-Red (IR) and RGB cameras mounted on the headset. Another domain where VR systems are getting increasingly more attention is the medical domain. The use of VR in the medical domain first appeared in the 1980s [6], when several applications were developed to train medical surgeons, such that in real situations, the rate of mistakes would be lowered. Then, in the 2000s, the focus of VR in medical situations shifted from surgeons and medical staff to patients by using the VR worlds for reducing the pain during medical operations in such a way that no medicines were used. The patients in such cases were placed in familiar, relaxing environments, \"tricking\" in this way the pain receptors in their bodies. Nowadays, the VR applications in this industry are used to train and plan a medical surgery ahead of the actual surgery, as described by the flow diagram from Figure 4.  
Figure 4: Flow diagram of using VR in surgery. Figure 3: Google Glass. Similar to the VR applications, and since 2013, the AR applications started to gain ground not only over a significant number of domains, but also over the VR world. AR applications were first developed around six domains: medicine, manufacturing, visualization, robot path planning, military, and entertainment [7]. In the medical domain, the AR applications are usually displayed by using a simple monitor that is near the doctor, an overlay with a radiography that is perfectly positioned on the patient. In this way, the doctor can perfectly see where the operation should be performed. Moreover, by using AR applications, the doctors do not need to interact with the radiographies or other physical elements that could compromise the sterility of the medical instruments. In the tourism domain, because of the development of mobile phones and with the appearance of smartphones and tablets, the AR applications started to be used more and more by tourists. Because of this, for example, the government of Italy and the leaders of the Tuscany region seized the opportunity and developed Tuscany+ [8], presented in Figure 5.  
The application works by pointing the camera at a landmark within the Tuscany region, and the application recognizes it. Then, after the landmark is identified, the application accesses the internet by navigating to different verified websites, like Wikipedia or Google Places, via the Google Places API (v3) under the Google Maps Platform, obtains information about the respective landmark, and shows it on the screen for the user.