Videogrammetric monitoring of as‐built membrane roof structures

Abstract

A monitoring system that uses applied geomatics techniques, including videogrammetry and terrestrial laser scanning, has been developed in order to investigate the dynamic behaviour of as-built membrane roof structures. To accommodate the problems involved in measuring such roof structures, examples of which include uniform surface texture and unreachable height, the system adopts a non-contact targeting methodology to substitute for traditional control techniques. In-house software was developed for processing the acquired video imagery in order to produce a sequential surface model of the membrane. This paper firstly reports on experiments conducted to demonstrate that the monitoring system was capable of measuring representative test structures with a precision of better than ±1 mm. To prove the feasibility and transferability of the system, videogrammetric monitoring campaigns were subsequently performed at a real-world test site where two different types of membrane structure were observed. The sequential 3D surface models that were generated allowed the displacement of the membrane surfaces to be investigated over a period, during which the range of the movement reached over 20 mm. The information acquired from the system is proving to be of great value to structural engineers involved in research and development of such membrane structures.

Deformation monitoring with off-the-shelf digital cameras for civil engineering fatigue testing

“…In addition, a permanent visual record is established for each observed epoch (Jiang and Jáuregui, 2007). Several research initiatives based on laser scanning (González-Aguilera et al, 2008;Gordon and Lichti, 2007;Lee and Park, 2011;Monserrat and Crosetto, 2008;Park et al, 2007;Vezočnik et al, 2009), photogrammetric (Barazzetti and Scaioni, 2010;Fraser and Riedel, 2000;Jáuregui et al, 2003;Jiang and Jáuregui, 2010;Lin et al, 2008;Mills et al, 2001;Whiteman et al, 2002) and range camera (Lichti et al, 2012;Qi et al, 2014) methods for deflection estimation exist so far.…”

Estimation of Vertical Deflections in Concrete Beams Through Digital Close Range Photogrammetry

“…This is why facilities, which cannot afford to purchase one, must stick to the digital photogrammetric means of 3D reconstruction. In order to achieve targetless point cloud generation, structured light can be used to supply surfaces with artificial texture sufficient for subsequent image matching by the means of projecting a random pattern during the data collection (Lin et al, 2008). In this way, Lin et al (2008) monitored the deformations of membrane roofs with a precision of 1.3-1.6 mm, where the scale was defined by imaging the footprint of a reflectorless total station.…”

Image-Based Deformation Monitoring of Statically and Dynamically Loaded Beams

“…Three digital cameras positioned at convergent geometry, and specially designed targets for a such high temperature environment were used to obtain a final precision for the reconstructed object space coordinates of 1 mm; et al (2003) used double sided targets and measured deflections in steel beams at an RMSE of 0.5-1.3 mm in an indoor laboratory. In addition, they also managed to measure the vertical deflections in bridge girders on a highway at an RMSE of 0.5-1.5 mm; Lin et al (2008) monitored the deformations of membrane roofs with a precision of 1.3-1.6 mm. Their system consisted of two machine vision cameras and one data projector, and it could operate without the use of traditional signalized targets.…”