Monitoring of Civil Engineering Structures using a State-of-the-art Image Assisted Total Station

Abstract

Today, many civil engineering structures are permanently monitored to provide early warnings from structural failure. Many of the currently used measurement sensors have the drawback that access to the monitored structure is required. Furthermore, different types of instrumentation are needed to measure vibrations and displacements. We therefore propose the usage of an image assisted total station (IATS) for vibration- and displacement monitoring. Compared to previously reported approaches using IATS prototypes, our system is based on a commercially available standard IATS. In laboratory investigations, we show that the used IATS can measure displacements with a precision of 0.1 mgon. In a field experiment at a lifesize footbridge we compare the IATS measurements to currently used accelerometer and total station measurements.

Vision-Based Bridge Deformation Monitoring

“…(i) supplementary measurement of camera motion (Ehrhart and Lienhart, 2015) and (ii) estimation of camera motion by tracking another target which is fixed in reality (Yoneyama and Ueda, 2012).…”

“…Ehrhart and Lienhart (2015) proposed a mixed system combing the camera with the total station. The total station provides angle measurement along the horizontal and vertical directions used to correct the camera motion influence.…”

“…For various vision-based systems in the literature, the hardware is almost the same [except the mixed systems, e.g., combing the camera system with total station (Ehrhart and Lienhart, 2015)] while the main difference is in the video-processing packages. A typical video-processing package can be decomposed into three components according to the procedures of measurement goal realization.…”

“…The scaling factor method using the camera-to-target distance (Khuc and Necati Catbas, 2016;Yoon et al, 2016) or merging optical system with a total station (Charalampous et al, 2015;Ehrhart and Lienhart, 2015) has no requirement about known geometric information. However, these applications are based on the prerequisite that the camera principal axis is perpendicular to the target surface plane and are thus not suggested.…”

A non-contact vision-based system for multipoint displacement monitoring in a cable-stayed footbridge

“…However, the method is sensitive to lighting changes [23,49] and changes of background conditions. [50] Also, the method is not the ideal choice for tracking slender structural components, because a rectangular template might include background pixels that move differently from the structural elements. Feature point matching is an alternative for the target tracking based on the key-point detection and matching.…”