Matching Construction Workers Across Views For Automated 3D Vision Tracking On-Site

Computer vision based tracking of construction resources is one of the several options available for obtaining trajectories useful in safety and productivity applications. This type of tracking requires that targets are accurately matched across multiple camera views to obtain a 3D trajectory out of two or more 2D trajectories. This matching is straightforward when it involves easily distinguishable targets in uncluttered scenes. This can be challenging in industrial scenes such as construction sites due to congestion, occlusions and workers in greatly similar high visibility apparel. This paper proposes a novel vision based method that addresses all these issues. It uses as input the output of a 2D vision based tracking method and searches for potential matches in three sequential steps. It terminates only when a positive match is found. The first step returns the strongest candidate by correlating a segment of workers’ past 2D trajectories. The second employs geometric restrictions, whilst the third correlates colour intensity values. The proposed method featured a promising performance of 97% precision, 98% recall and 95% accuracy.