Fusing 4D modelling and laser scanning for construction schedule control

The construction industry remains one of the riskiest of all. This risk is mainly the result of a poorly controlled, and thus uncertain, environment. For instance, construction progress is often improperly controlled, resulting in some unnoticed errors with considerable impact on later project activities, and ultimately project success. Better progress control requires, among other things, better project three-dimensional (3D) as-built status control. Until recently, comprehensive and accurate 3D as-built status control remained almost impossible because the lack of adequate technology made it too time- and labour-intensive. However, the progress made in the last two decades in 3D (even 4D) modelling, and more recently in laser scanner (and also photogrammetry), is such that fast and accurate 3D as-built status control is now conceivable. In this paper, a system for automated construction progress control using laser scanning and 4D modelling is presented. Given a laser scan of a construction site and its acquisition date, the system quasi-automatically recognizes the building elements that (1) are expected to be built at that date and (2) visible in this scan. Results from multiple scans obtained on the same date but from different locations can be aggregated, and the combined recognition results are used to automatically infer site progress status, and consequently update the schedule. Experimental results demonstrate these features and the significant potential of this approach.