title: A synchronized multipoint vision-based system for displacement measurement of civil infrastructures.
abstract: This study presents an advanced multipoint vision-based system for dynamic displacement measurement of civil infrastructures. The proposed system consists of commercial camcorders, frame grabbers, low-cost PCs, and a wireless LAN access point. The images of target panels attached to a structure are captured by camcorders and streamed into the PC via frame grabbers. Then the displacements of targets are calculated using image processing techniques with premeasured calibration parameters. This system can simultaneously support two camcorders at the subsystem level for dynamic real-time displacement measurement. The data of each subsystem including system time are wirelessly transferred from the subsystem PCs to master PC and vice versa. Furthermore, synchronization process is implemented to ensure the time synchronization between the master PC and subsystem PCs. Several shaking table tests were conducted to verify the effectiveness of the proposed system, and the results showed very good agreement with those from a conventional sensor with an error of less than 2%.
authors.affiliation: Department of Civil and Environmental Engineering, Sejong University, Seoul 143-747, Republic of Korea.
authors.forename: Hoai-Nam
authors.initials: HN
authors.lastname: Ho
authors.forename: Jong-Han
authors.initials: JH
authors.lastname: Lee
authors.forename: Young-Soo
authors.initials: YS
authors.lastname: Park
authors.forename: Jong-Jae
authors.initials: JJ
authors.lastname: Lee
mesh_terms: D000465:Algorithms; D002138:Calibration; D003199:Computer Systems; D060389:Construction Industry; D004738:Engineering / Q000295:instrumentation* / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D020407:Internet; D012984:Software; D055883:Structure Collapse / Q000517:prevention & control; D013997:Time Factors; D014741:Video Recording / Q000295:instrumentation* / Q000379:methods