M. Jenewein, P. Ferschin:
"Validation of Construction Deviations using Parametric BIM and Augmented Reality";
Talk: 19th International Conference on Construction Applications of Virtual Reality (CONVR2019), Bangkok, Thailand; 2019-11-13 - 2019-11-15; in: "Proceedings of the 19th International Conference on Construction Applications of Virtual Reality (CONVR2019)", (2019), 10 pages.

The use of Building Information Modeling (BIM) in the entire lifecycle of a building is becoming
increasingly important. The construction of buildings is quite often deviating from the original planning. Reasons
for discrepancies are errors in plans or in the building process. However, constructional modifications from the
building phase have to be updated to maintain consistent as-built BIMs, which can also lead to achieve digital
twins of built assets. Surveying for building reconstruction is normally done by using total stations, laser scanners
or photogrammetry. Planning corrections are performed later on, manually at the office. Possible errors in this
process can occur during the data collection, the data transfer and in 3D modeling. To overcome this large effort
for manual updating of BIMs we propose a new real-time method based on parametric BIM and Augmented Reality
(AR). The fundamental approach is that on-site augmentation of planning data should match the real building
situation. Recognizable differences in AR will indicate potential building deviations. Necessary adjustments of the
parametric BIM to the physical building structure in AR are performed by using a wireless connected handheld
tablet for manual user interaction. BIM by nature is parametric and object oriented. But because of missing
interfaces for parametric data exchange directly into AR, at the moment conventional BIM software is not quite
adequate for real-time editing of BIMs by using on-site AR. Therefore, the prototypical implementation has been
performed using Unity as parametric developing environment and Vuforia as an extension. Precise augmentation
is enabled through tracking by use of image targets, multi targets and an AR camera. The proposed method has
been developed and tested using a prototype scale model as laboratory environment and could be validated
through a real-world industrial use case in the environment of a cement loading facility. The results show that the
parametric BIM-AR method is very sensitive to smallest changes of surrounding conditions. But the outcome also
demonstrates that on-site tracing of construction deviations using BIM and AR is already possible.

As-built BIM; Parametric BIM; Augmented Reality.