# AR in the Architecture Domain: State of the Art
## 8 Applications
### AR for the Architectural Design and Building Process  
The relationship between built architecture, design tools, and the use of AR technologies to simplify specific construction steps is a topic that began almost two decades ago and has found a very fertile research ground in architecture [187]. Today, augmented reality (AR) plays a relevant role in Industry 4.0, showing great potential within the construction industry [188]. One of the most important contributions in the architectural design domain is in representing a full-scale virtual model to visualize the project on-site [189]. This supports all actors involved in the process, from architects to interior designers, from structural designers to clients, employers, and workers. AR may support the entire design chain of a building, simplifying the reading, interpretation, and implementation of that complex intersection of activities expected in the AEC domain, and increasingly systematized by the lean and BIM processes. Some current states of the art [28,190] have highlighted the potential of AR in simplifying and optimizing that process and improving both the design and construction processes [191], emphasizing the integration between AR and BIM in the workflow [192]. Others have highlighted how AR can make BIM/CAD ubiquitous throughout the AR-BIM process, supporting and improving the management and budgeting of the artifact by analyzing critical consumption issues [193]. Augmented reality, therefore, is proving to be a supportive tool for every aspect of the construction life cycle:  
* In project planning and co-design activities, the user can preview and share the building and urban context simulation. Urban/architecture planning requires a hierarchy of decision-making activities, enhanced, and optimized by collaborative interfaces. Co-design activities may involve both specialists and citizens, offering a decisive role in the urban and architecture pre-organization choices. Augmented reality can assume the role of a co-working platform. At the urban scale, AR is considered a practical design and collaboration tool within design teams. One of the first examples has been the ARUDesigner project, evaluating virtual urban projects in a real, natural, and familiar workspace [194]. Urban areas represent a meeting point between stakeholders' needs and public needs. For that reason, participatory processes are necessary, and AR can increase the range of participants and the intensity of participation, engaging citizens in collaborative urban planning processes [195]. At the architectural scale, before construction, virtual walks around the future buildings may identify changes that must be applied without causing problems and delays in the building execution phase. In this way, communication delays can be minimized, optimizing project management processes [196]. Some applications can overlay actual design alternatives onto drawings through MARs, allowing for flexible wall placement and application of interior and exterior wall materials, developing new, engaging architectural co-design processes [197]. Multitouch user interfaces (MTUIs) on mobile devices can be effective tools for improving co-working practices by providing new ways for designers to interact on the same project, from the cognitive and representation points of view [198];
* In the construction monitoring process: the real-time overlap between the design and the as-built model allows for sudden validation of the progress of construction. It can also highlight the inconsistencies between the design documentation, 3D model, and the actual state [199], assessing their effects and allowing for rapid response, reducing project risk. Structural elements can be monitored from the early construction stagesto their maintenance [190].