Authors:
Shakhzod Takhirov
1
;
Mukhady Israilov
2
and
Sultan Kudratov
3
Affiliations:
1
Department of Civil and Environmental Engineering, University of California, Berkeley, U.S.A.
;
2
Joint Research Institute of Russian Academy of Sciences (KNII-RAN), Grozny, Russian Federation
;
3
Department of Information Technologies, Tashkent University of Information Technologies, Tashkent, Uzbekistan
Keyword(s):
Laser Scanning, Point Cloud, Experimental Earthquake Engineering, Mirror Reflection, 4D Surface Tracking, Surface Deformation.
Abstract:
A laser scanner is an optical instrument that emits laser beams toward objects surrounding the scanner and measures the location of the objects’ points in space. As a result, it collects the so-called point clouds. In experimental earthquake engineering, the laser scanners have been used in many applications. In quasi-static testing, they used for four-dimensional tracking of the test specimen's condition in three spatial coordinates and time. When a single scanner is used, the object's rear surface is in shadow zone and as such, the points of the rear surface are not collected. To acquire the point cloud of the object's rear side two commonly used options are utilized. In Option 1, several scanners working in parallel can be deployed. In Option 2, the same scanner can be moved to other positions to cover the shadow zones. Option 1 represents an expensive option that requires an investment in two or more scanners, finding a way of triggering them simultaneously, and time required for
registration of the point clouds collected by several scanners. The main shortcoming of Option 2 is that is does not allow simultaneous scans from both sides and registration of the laser scans from many different points can be time consuming. To overcome shortcomings of these two options, this paper introduces a novel approach (Option 3) of using several mirrors strategically placed in respect to a single scanner to cover the shadow zones with a single scanner and from the same position. To ensure cost-effectiveness of the approach, this research was focused on the utilization of affordable and commonly used rear-reflective mirrors. This paper investigates the point clouds obtained from the mirror reflections and quantifies the quality of these data by estimating accuracy and reliability of the reflected point cloud data. The theoretical estimates were verified by laser scanning of sample test specimens.
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