Augmented reality (AR) is a rather old technology that has been constantly evolving over the years and has become particularly popular in the last decade due to advancements that have made this technology accessible to the broader public. The Sword of Damocles, a head-mounted display application developed by a Professor named Ivan Sutherland in 1968 ^[1], is widely considered to be the first AR system. AR applications can today be experienced through mobile devices, and this is the cheapest way to experience AR, which can also be experienced through head-mounted devices such as MetaQuest3, Apple Vision Pro, and Microsoft Hololens. Tech giants such as Meta, Apple, and Microsoft are heavily investing in AR technologies, and experiencing AR through their products is more impressive than experiencing AR through mobile devices. However, mobile devices are cheaper and are owned by almost everyone, and this is an essential factor that has contributed to the increasing popularity of AR. Google and Apple have also created software development kits (SDKs) that enable programmers to develop AR mobile applications (i.e., ARCore and ARKit).

AR creates a digital information layer that is placed on top of our real world, and as depicted in Figure 1, AR applications occupy a position that is closer to the left end of the “virtuality continuum”. In this continuum, the real-world environment is situated at the left end, and the fully immersive virtual environments are located at the right end. The intermediate space between the two ends is known as mixed reality, a space where various levels of integration between virtual and real-world elements co-exist ^[2] (Figure 1).

Over the evolution of AR technology, a number of categorizations have been proposed by various researchers. One widely recognized taxonomy focuses on how the AR experience is activated, and according to this taxonomy, we have the following categories:

Marker-based AR relies on scanning markers, such as 2D images or 3D objects (e.g., paintings, statues, signs, etc.), to activate an augmentation, that is, digital content placement onto the real world. Scanning is typically carried out with a camera that is typically present in today’s mobile devices (smartphones, tablets). The digital content can include multimedia elements such as 2D and 3D images, animations, video, text, narration, and sound effects.

Markerless AR does not require physical markers. In this case, users select digital content from a menu, which is then placed into the real world on demand. Markerless AR is supported by mobile applications or AR-capable headsets such as Microsoft HoloLens, MetaQuest 3, or Apple Vision. When mobile devices are used to experience markerless AR, digital content is often displayed on flat surfaces like tables or floors. The scientific literature identifies two types of markerless augmented reality: location-based AR (which will be described in the next section) and projection-based AR. Projection-based AR utilizes specialized types of projectors to display multimedia content, typically visuals in 3D form, on flat, two-dimensional surfaces such as the walls of buildings with special interest (e.g., municipalities, castles, palaces, etc.)

Location-based AR (LBAR), also known as location-aware AR, is a technology that is either mentioned in the bibliography as a subset of markerless AR or as a different discrete category. This type of AR does not require physical markers to trigger the AR experience, and augmentations are activated when users approach specific points of interest (POI) in the real world. In order to detect the user’s location, these applications can utilize real-time positioning systems (RTLS), such as GPS sensors, gyroscopes, magnetometers, beacons, etc. In outdoor settings, GPS sensors are the most common technology that is used to track the user’s position. However, a problem that may be encountered is that environmental factors like tall buildings or hills may obstruct signals and affect GPS accuracy. To overcome this problem, complementary technologies like visual localization algorithms, WiFi-based positioning, and inertial navigation are often employed.

Indoor positioning systems (IPS) are used for indoor environments like museums, where GPS lacks precision or does not work at all. These systems rely on technologies such as radio signals, optical systems, or Bluetooth beacons (e.g., iBeacons) to track users’ positions and trigger digital content on mobile devices. Beacons broadcast identifying signals that allow mobile devices to determine proximity levels—immediate, near, or far—enabling precise location-based AR experiences and different AR game scenarios. Furthermore, several museums use beacon-based AR technology to replace traditional audio tours, delivering multimedia-rich information about exhibits directly to visitors’ devices.

Furthermore, certain software packages also provide other simple ways of achieving an AR experience. For example, the software AR development environment Taleblazer (a product of the Massachusetts Institute of Technology-MIT, Cambridge, MA, USA) provides an alternative way with password-protected agents. When users are close to a point of interest, they can unlock the digital content of the experience by providing a password typically placed somewhere in the real space, such as stickers or signs placed near the points of interest.

Location-based augmented reality applications, also known as location-aware AR, are not a new technology but rather technology that has existed for several years. However, these applications became widely popular after the release of two well-known location-based AR games, Ingress and Pokémon Go, which were developed by Niantic in 2014 and 2016, respectively, for Android and iOS devices ^[3].

Ingress is a mobile application that utilizes the GPS sensor of the mobile device (smartphones and tablets). In this app, users are prompted to locate and interact with “portals” close to their GPS location. Portals are points of interest, such as buildings or landmarks with historical value and unique architecture (monuments, statues, murals, etc.), and other types of places that may interest the wider public, such as libraries, churches, memorials, places where public art is displayed, parks, etc. Furthermore, the application combines gamification (e.g., gathering points) and storytelling. Pokémon Go is another mobile game where users are prompted to utilize their mobile device (smartphone or tablet) GPS to find and interact with virtual Pokémons, which are visible in the real world through the mobile device’s camera. The concept behind these applications was to transfer the game action from personal computers to streets and other locations in the real world.

Other known applications are the following:

Google Maps Live View ^[4] offers two views for walking navigation: the 2D map and Live View. The Live View feature, available for specific places in the world, utilizes the users’ phone camera to recognize their surroundings and to display virtual pointers and arrows that aid users in navigating to their destination. In addition, information is displayed regarding the buildings and attractions, such as the distance from where the users stand, the opening hours of the facilities, and the services they offer, including visitor photos and reviews.

Sky Guide, developed by Fifth Star Labs LLC ^[5] is an educational astronomy tool that displays detailed information about the constellations visible from the user’s current location. Similar apps include Star Walk, Sky View, and Star Chat.

Location-based augmented reality (AR) games are now utilized across various domains, including entertainment, education, marketing, and tourism. These applications often also serve multiple purposes simultaneously. For instance, location-aware AR games created for tourism can entertain visitors while educating them about different aspects of the destination, such as its cultural heritage, history, and the natural environment (e.g., mountains, rivers, and wildlife).

The focus of this paper will be location-based AR applications in education.