The presented approach has been used in the European Union Fifth Framework Program IST project ARCO—Augmented Representation of Cultural Objects [3, 18, 26, 28].
Fig. 6.6 Archaeology lesson—example of question visualization
Within the project, a set of tools have been developed to enable museums to build interactive augmented reality environments for presenting cultural objects based on three-dimensional models of the objects [30]. In this system tracking of real objects is performed by the ARToolKit library (Sect. 6.2.1). The AREM approach can be applied to teaching in different domains, such as chemistry, physics, geography, biology, cultural heritage, etc. [27]. As an example, an interactive presentation about excavated pottery, which can be used as a teaching material during an archaeology lesson, is shown below [32]. An example augmented reality environment presented to a user is depicted in Fig. 6.6.
The 3D model of an artifact and a question are displayed on one of the physical markers, while three possible answers are displayed on three other markers. The model is being automatically rotated, so a user can see it from different angles. The model can be also manipulated by moving the marker. There is also a command displayed at the bottom of the window informing users what they should do. A user can answer the question by flipping one of the answer markers. Depending on whether the answer is correct or not, an appropriate 3D model appears expressing approval or disapproval. In addition, accompanying sound can be heard. A number of game points for each correct answer can be scored. In the case of a wrong answer, the number of points to score is decreased. For each model presented, several questions can be asked. When all questions have been answered, the user can continue the quiz and learn more about subsequent objects.
Fig. 6.7 Augmented reality environment for performing a chemical experiment
Another example application of augmented reality environments is teaching chemistry [32]. The main features of the AREM approach are exemplified by an acid-base experiment conducted in an ARE. The augmented reality environment is built by using the prototype AREPS system. When the environment is created by the AREPS system, a user can see the view shown in Fig. 6.7.
The environment contains two beakers with the phenolphthalein and HCl solutions standing on the caption boxes with appropriate labels, the measuring cylinder with the NaOH solution, the pipette, and three physical square cards with special markers printed on their surfaces for tracking. The cards are real objects that are tracked in a real environment and can be assigned with Real AR-Objects contained in an augmented reality scene used to create an ARE. At the beginning of the experiment, the user should drip some quantity of the phenolphthalein solution into the NaOH solution. The learner by manipulating the card can draw the phenolphthalein solution into the pipette. To this end, he/she has to move the pipette close enough to the beaker with the solution. While the tapered pipette end is being located close enough over the beaker, the pipette is filling with the solution. Next, the user should drip the phenolphthalein solution into the NaOH solution by placing the pipette end over the measuring cylinder.
The root of the augmented reality scene shown in Fig. 6.7 is an AR-Scene composed of two Virtual AR-Objects: the caption boxes highlighted with a green border. Also, the AR-Scene contains four Virtual AR-Objects highlighted with a blue border and two Real AR-Objects highlighted with a red border. In the ARE there are also physical objects that are not modeled in the augmented reality scene, such as the card with the letter C. The caption boxes are virtual components of the AR-Scene geometry (i.e., composition relationship), whereas other Virtual AR-Objects are contained in the AR-Scene (i.e., containment relationship). The Real AR-Objects contained in the AR-Scene are assigned to the cards. The cylinder and the pipette are attached to the two cards. The Real AR-Objects assigned to the cards have virtual geometry with labels describing the content of the attached virtual containers. At the bottom of the presented view, there is a command overlaid on the ARE view, which informs a user what he/she should do.
Fig. 6.8 Dripping the HCl solution into the NaOH solution
In Fig. 6.8, a different stage of the experiment is presented. While the user drips the HCl solution into the measuring cylinder, which contains the NaOH solution mixed with the phenolphthalein solution, the cylinder content changes color from pink to colorless because the acid neutralizes the basic pH of the NaOH solution. The dripping should be continued until the mixture in the cylinder becomes colorless, which denotes that its pH is neutral.
Conclusions
The AREM approach presented in this topic enables building highly-interactive augmented reality environments that seamlessly combine virtual content with real environments containing physical objects. In those environments, users can interact with the content in a direct and natural way by manipulation of the physical objects. The most essential characteristics of the AREs created according to the AREM approach are: dynamic scene structure, dynamic content, interactive behavior of content, and intuitive user interaction using real objects.
The ARSM model formalizes the concepts of AR-Class, AR-Object, and their components. These concepts describe in a uniform way three categories of entities that can be found in AREs, i.e., real objects, virtual objects, and scenes comprised of real/virtual objects. Based on the object-oriented paradigm, it is possible to create abstraction of real objects, virtual objects, and scenes. Inheritance between AR-Classes enables content designers to define new AR-Classes by modifying and extending the structure and behavior of existing AR-Classes, which leads to decreased time required for content preparation in comparison to creating the content from scratch. By setting different attribute values, the visual and behavioral aspects of AR-Objects can be easily customized and adjusted to different needs of content creators.
In the context of the education domain, augmented reality environments give learners an opportunity to interact with the learning content in person. Thus, learners become more motivated to learn since they can actively participate in hands-on activities. The application of AREs in teaching chemistry leads to cost reduction due to replacing real expensive resources, such as laboratory equipment and supplies, with their virtual counterparts. Another significant advantage of AREs is safety since unskilled learners may explore potentially dangerous situations without any risk of harm to themselves or damage to expensive equipment. Learning in the AREs can be particularly attractive and evocative for younger generations, by whom it can be perceived more like entertainment rather than learning.
