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Augmented reality technologies

in everyday con­struc­tion

by Luca Montagna, 
member of the BIM team Gruner Group, luca[punkt]montagna [ät] gruner[punkt]ch

Augmented reality (AR) technologies are gaining ground and arouse great interest in the construction industry. The field of application of these technologies is particularly versatile in planning and execution - starting with the visualization of the first draft of a construction project for a customer up to the target-performance comparison of the executed planning on the construction site. 

The Gruner Group's BIM team procured and tested a Microsoft HoloLens in November 2017. The HoloLens is currently sold as a Developer Edition mainly to developers. To use it, we have set up HoloLens to display IFC files. The development of applications for the HoloLens is relatively complex and therefore not suitable for a standard user. On the one hand, the developer must have a profound knowledge of the Unity development environment and, on the other hand, handling holograms is not entirely easy.

In the Gruner Group, the focus was not on developing applications, but on using HoloLens as a planning tool. HoloLens does not currently support IFC models, so our projects first had to be converted to FBX format to make them readable at all. In the context of my intermediate diploma thesis during my current computer science study at the higher vocational school Uster, I programmed a converter for the Gruner group.

After converting the IFC file, the model can be displayed with the free FBX viewer from Microsoft. The viewer can easily open models up to about 5 to 7 MB. Once the models have been opened, they can be moved, rotated or scaled. This makes it possible, for example, to place models on the work table in order to view them in a comfortable size. The models appear in good quality, but details are less clear, as the HoloLens cannot produce enough light points to make the model sharp.

From 8 MB the hardware resources of HoloLens become scarce. After a certain number of meshes, the viewer can no longer render any more meshes, which means that some models are “chopped off” and thus displayed unattractively and incorrectly.  

Using the current HoloLens as a controlling tool in the office is not very efficient and therefore not useful due to the blurred presentation of larger models. As a customer presentation tool, it is suitable for smaller models or model sections, and can only be used to a limited extent for a comprehensive model presentation, since large models (such as the model of the “Grosspeter Tower Basel” cannot be opened.

This technology will certainly progress in the future to such an extent that the above-mentioned fields of application can be fully covered. HoloLens can only be used to a limited extent in its current developmental stage.

Luca Montagna is member of the BIM team Gruner Group, luca[punkt]montagna [ät] gruner[punkt]ch