Simplification & Visualization of BIM models through Hololens

Abstract

Augmented Reality (AR) is the technology that superimposes digital generated objects on the physical world. It has the potential to create new products and services,like visualizing future buildings or objects that will decorate a place, which creates new opportunities for applications in both the public and private sector. The architecture and construction fields are particularly interested in investigating this innovative technology to engage stakeholders, such as designers and engineers, in every stage of decision making and to minimize discrepancies between the original design of a building and the final outcome. Portability is one of the greatest advantages of Head-Mounted Display (HMD) AR technologies, but there are limitations regarding the amount of data which can be visualized using the computational power of the current generation of devices. Also, automated methods and approaches that can cope with the intricacy of the models have to be produced and tested to make the usage of augmented reality feasible.Within this thesis, a methodology is developed to isolate each storey of a Building Information Modeling (BIM) model and its exterior envelope. Firstly, the model was converted, from the Revit file format, to the open standard Industry Foundation Classes (IFC), which made the file human readable. Only semantic information was used to isolate each storey of the building, while for the extraction of the outer shell geometrical calculations were performed. This extraction took place by sending rays from one side of the model to the other and checking the intersection of the rays with the model.Afterwards, the storeys and the exterior were visualized through an AR device,the Hololens. The Unity platform, which provides many tools for holographic development, was used for the configuration of the scene where the final user will interact with the created models. Scripts in the C# programming language were developed to allow interaction between the user and the holograms. I created a simple and intuitive menu, consisting of 3D buttons to allow the user to visualize only the desired parts of the model. After having visualized the model, the user has the ability to scale and rotate the model using the corresponding buttons. In the same way, when the user stares at an element of the building, this element is high-lighted and by making the tap gesture, he/she can visualize metadata information about this element as text above the model. Finally, spatial perception functionality is provided by virtually placing the model on horizontal planes identified by the device.The proposed methodology was tested in a use case on a sample BIM model, and specifically of the Amsterdam Medical Center. The large size of the file and the high complexity of its geometry made the model a challenging test that made it possible to highlight the limitations and efficiency of the developed approach. Despite the positive results of the process, the accuracy is affected by the computational power of the current generation of hardware. Nevertheless, the clear perception of a construction coupled with the interactions capabilities provide an immersive experience which can actively involve the user with the visualization process