Mobile Augmented Reality for Building and Construction

We describe a software architecture for providing mobile user at the construction site with two­way real­time augmented reality access to 4D CA D a nd BIM i nformation. T he s ystem a llows t he user to compare scheduled building information models with the situation at the construction site in real time, as well as to attach position and time aligned visual and other feedback to the building models at the office. 1 I NTRODUCTION Building and construction is widely recognized as one of the most promising application fields for Augmented Reality [1, 2]. Recent developments in mobile processing units, camera quality, different sensor s, wireless infrastructure and tracking technology enable AR applications to be implemented even in demanding mobile environments [3]. Building Information Models (BIM) are another main technology driver increasingly used for data sharing and communication purposes in real estate and construction sector [4]. Combined with Augmented Reality, 4D BIMs could facilitate comparisons of the actual situation at the construction site with the building’ s planned appearance at the given moment. Such mobile augmented information available at the construction site would have various applications for construction work planning, verification, training and safety, as well as for communication and marketing prior to construction work. The related camera tracking technologies open up further application scenarios, enabling us to implement mobile location based vi sual f eedback f rom the c onstruction s ite t o t he CAD a nd BIM systems. We may think of adding elements of reality e.g. images, reports and other comments to the virtual 4D model, with full awareness of the user’ s location in time and space. Altogether, the tracking and interaction techniques can thus be made to serve the complete spectrum of Mixed Reality [5], forming a seamless interaction cycle between the real world (augmented with virtual 3D/4D model data) and digital building information (augmented with real world data): see Figure 1. The AR4BC project (Augmented Reality for Building and Construction) between VTT and industrial partners from the Finnish B&C sector aims to providing the mobile user at the construction site with direct two­way access to 3D CAD and 4D BIM information. Our article describes the overall AR4BC software architecture, from content creation (4DStudio) and positioning tools (MapStudio) through onsite visualisation (OnSitePlayer) and wireless data sharing (OnSiteServer) up to mobile interaction and visualisation (OnSiteClient). Special emphasis is on authoring tools, i.e. managing different model formats, linking them to 4D information, placing the models in geo coordinates, as well as managing complex data intensive building model information on thin mobile clients. We also discuss model based tracking and other methods to match the camera view with the virtual model description of the building and its environment, visualisation and interaction tools, as well as the feedback mechanisms to be enabled.