Deformation Monitoring System Based on 2D-DIC for Cultural Relics Protection in Museum Environment with Low and Varying Illumination

Abstract

Quantifying the condition of large cultural relics, such as marine archaeological shipwreck, is important to verify stability and reliability. Deformation monitoring system plays a key role in the preservation and long-term conservation of cultural relics. Two-dimensional digital image correlation (2D-DIC) method has proven its efficiency in being able to provide accurate quantitative information of structural deformations. In this study, a deformation monitoring system with four cameras based on 2D-DIC is developed to perform noncontact, optically based measurement to monitor the deformation of shipwreck in museum environment with low and varying illumination. Because the consistency of the accuracy of 2D-DIC measurements for different locations is the most basic requirement in the application of structural deformation monitoring, selecting the appropriate exposure time and quantifying the bias errors on 2D-DIC measurements should be helpful to the optimal use of this optical nondestructive testing technique. A theoretical criterion is deduced to quantitatively characterize the dependence of interpolation bias upon natural patterns and illuminations. Then, an exposure adjustment scheme is built based on the aforementioned criterion. Numerical experiments reveal that the exposure adjustment scheme is able to provide consistency interpolation error for different natural patterns even though the environmental illumination is different as well. The deformation monitoring system with the proposed exposure adjustment scheme is promising for developing flexible and robust in situ structural health monitoring for use in museum environment with low and varying illumination, making 2D-DIC technique a really useful tool for in situ long-term monitoring of large cultural relics.

High Accurate Crack Reconstruction Based on an Improved Discontinuous Digital Image Correlation: Subset Restore and Adaptation Method

“…Digital images for validation of the DIC method were mainly acquired from laboratory experiment [10][11][12][13]34] and digital simulation [35]. Although a laboratory DIC experiment is a complex procedure, a typical digital simulation to obtain reference and deformed images is much easier based on the assumption of deformation.…”

“…e accurate measurement and reconstruction of surface displacement, deformation, and crack status are the key to the acquisition of qualitative and quantitative information to better understand the mechanism of load-resistance and the failure modes of cracked structure. A feasible noncontact surface displacement measurement method is the digital image correction (DIC) method, which was proposed by Peters and Ranson [8] and Yamaguchi [9] and tested by Chu et al [10][11][12][13]. Nevertheless, the standard DIC method is based on the hypothesis that the pending surface is continuous everywhere, which will lead to serious errors in the vicinity of cracks.…”

Energy balanced routing protocol based on improved particle swarm optimisation and ant colony algorithm for museum environmental monitoring of cultural relics

“…Among them, energy consumption is critical. However, the energy of sensor nodes in WSNs is strictly limited [23][24][25]. Once some nodes in the network run out of energy due to frequently sending and receiving data, energy holes occurred, network life cycle will be shortened, and the reliability of the system will be affected [26].…”

Ex-situ deformation measurement system based on dual-reflector

“…[7][8][9] The 2D-DIC system [10][11][12] only needs a single camera and has been widely used in practical measurements. [13][14][15] A basic principle for the 2D-DIC measurement of specimen surface deformation is that the original position of the specimen before and after deformation is fixed, that is, this position remains in an in-situ state. However, when affected by the mechanical vibration of the experimental equipment or other human factors, the specimen is displaced from its original position, thereby generating out-of-plane rigid motion (OPM) and in-plane rigid motion (IPM).…”