Implementation of virtual reference points in registering scanning images of tall structures

Abstract

The concept of obtaining uniform and high-precision 3D models of large and complex engineering structures based on terrestrial laser scanning surveys highly depends on the accuracy of registering a series of adjacent scans. If it is not possible to place the required number of reference points in the observation scene, and there are no identifiable structural elements that could serve as such reference points, the issue can be solved by using the virtual reference points. The virtual reference points are not marked, but their position can be re-created in the post-processing of the scans on the basis of the geometrical features of the object. In the case of an industrial chimney, these can be the structural axis points determined at arbitrarily selected altitudes. In the solution presented herein, the coordinates of the reference points were independently determined twice: in the geodetic coordinate system using traditional method, in the local system of the scanner using the bisector of the chord of the circle, and by approximation of the circular arc shape of the chimney shell. Both procedures are preceded by the filtration of outliers. The concept of virtual reference points was verified by the measurement of the verticality of the axis and the structural geometry of a steel industrial chimney, which was accessible only on the foundation level.

Analysis of Two-Option Integration of Unmanned Aerial Vehicle and Terrestrial Laser Scanning Data for Historical Architecture Inventory

“…This confirms the correct measurement and data processing. The accuracy of the prepared network meets the assumptions of the conducted research and is consistent with the experience of other authors (Granek et al, 2020).…”

User Oriented Calibration Method for Stonex X300 Terrestrial Laser Scanner

“…However, in the Stonex X300 device, the values are computed from point cloud coordinates based on the cosine Law formula following Eq. (6)(7)(8). Figure 4 and Figure 5 show the analysis of the angular measure in seconds for both horizontal and vertical angles based on observation set 2, following configuration settings illustrated in Figure 2 (b).…”

“…Therefore, individual calibration scenarios are highly recommended when accuracy is the main concern in a particular applications [4] [5]. Stonex X300 is a pulsed mid-range TOF terrestrial laser scanner (TLS) device that shows the potential to deliver accurate range measurements in mid and close-range applications [6] [7]. However, close-range measurements from this device counter instability in precision measures due to the accumulated level of noise delivered from measurements referenced to multiple effects such as the incidence angle of a laser beam, weak laser returns, limitations in signal post-processing returns, and range-finder precision capabilities [8] [9].…”

3D Finite Element Analysis of a Concrete Dam Behavior under Changing Hydrostatic Load: A Case Study

“…In the last decade there were attempts to obtain high-quality 3D models of surface geometry, based on terrestrial laser scanner (TLS) measurements, which were applied to different complex and large structures [ 25 , 26 ]. There were also some studies on the use of TLS measurements to monitor the deformations of hydraulic structures [ 27 ], but in this case very accurate instruments and very reliable measurements are needed.…”