# AR in the Architecture Domain: State of the Art
## 3 AR Project
### AR Aim and Users  
A careful evaluation of the AR system's communication aims and the users' target is fundamental in AR projects. The former identifies different levels of application, which can be expanded in several architectonic areas. It is interesting to highlight that the topic of architectural communication through AR is often deepened in the starting aim or the result of the research, but it is not self-consistent. Moreover, the word \"communication\" is frequently replaced by valorization and promotion terms. In general, the attention is focused on storytelling, strongly linked to the objectives of the project and the technology used [32]. A second aspect is related explicitly to AR's communicative and collaborative capacities [33], outlined in the architecture domain [20].  
Suppose that the communication aims are set concerning the final users; in that case, it is appropriate to speak of levels of knowledge transfer, understood as clustering between groups that present homogeneity in terms of relationships and content, according to a qualitative analysis. The topic of knowledge transfer is extensive and related to multiple variables, from content creators to users, passing through the medium of communication and the environment in which it takes place. An interesting state of the art in this sense is offered by [PERSON] et al. [34]. This division highlights the three levels of knowledge transfer: reception, adoption, and utilization of knowledge. These three areas can be expanded and outlined in architecture, suggesting a simplified version based on the author's experience in the domain. The main aims are clustered by the level of depth and the content complexity, as follows:  
* Inform, promote, guide (Level I of knowledge transfer);
* Teach, learn, know (Level II of knowledge transfer);
* Design, interpret, understand (Level III of knowledge transfer).  
Figure 5: Graphical diagram with some domain variables.  
In this suggested hierarchical structure (Figure 6), the first level represents the synthetic and simplified information, reaching the widest audience of users for a purely informative purpose without feedback. This level can be applied to most of the activities and application domains. An example is the cultural learning domain [35], which combines cultural promotion, engagement, and all those applications related to architecture, engineering, and construction (AEC) to support use, assembly, and preliminary analysis. In the second level, the virtual data must be designed to show concepts and calibrated for a more limited user, providing a feedback system on the AR used and the knowledge acquired. Here, AR communication is not a one-way information process, but aims to take root in the user, integrating with previous knowledge. To this level, all the educational paths related to architecture are mainly outlined in the teaching domain [36], construction training for public and private users, and tourist routes that provide specific learning tours. The last level (Figure 6) is devoted to exploring content that is otherwise challenging to understand with traditional communication channels. It extends already established knowledge and increases awareness in the architecture domain. The AR audience is very restricted by the cultural background suitable for understanding and using the complex content transmitted. The communication includes a first learning step enriched by a system of interaction that assesses the level of knowledge and verifies the concepts transferred. To this level, all users carry out an activity that requires a preliminary understanding and interpretation of the artifact before starting paths of built management and transformation. In general, target refers to users employed in the design sector, from building redevelopment to restoration, conservation, and research paths.