A Comparison of TLS-based and ALS-based Techniques for Concrete Floor Waviness Assessment

Laser scanning-based techniques have been applied for checking the dimensional tolerances of concrete elements. Several studies utilized Terrestrial Laser Scanning (TLS) for measuring concrete floor waviness. The results of those efforts have shown that accurate floor waviness information can be obtained using TLS. Unmanned Aerial Vehicles (UAVs) mounted with cameras and 3D laser scanning sensors, referred to as Airborne Laser Scanning (ALS) hereafter, have versatile applications in construction, such as surveying, progress control, 3D modelling and inspections. As-built data collection for dimensional quality assessment can be a potential application of such technology. In particular, the application of ALS for assessing the waviness of concrete slabs warrants further exploration. This study presents the results of a comparative analysis of floor waviness measurement results obtained using ALS and TLS-based technologies. Continuous Wavelet Transform (CWT) is applied to the depth map derived from both point cloud datasets to obtain waviness information. Comparable results are obtained for the CWT scales of 30, 60 and 75. Detailed discussions on how the results can be improved are presented. The analysis of the accuracy of results obtained using ALS advances its application in the field of dimensional quality assessment.