{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,7]],"date-time":"2026-06-07T16:08:33Z","timestamp":1780848513797,"version":"3.54.1"},"reference-count":26,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2016,8,23]],"date-time":"2016-08-23T00:00:00Z","timestamp":1471910400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>An advanced video deflectometer using actively illuminated LED targets is proposed for remote, real-time measurement of bridge deflection. The system configuration, fundamental principles, and measuring procedures of the video deflectometer are first described. To address the challenge of remote and accurate deflection measurement of large engineering structures without being affected by ambient light, the novel idea of active imaging, which combines high-brightness monochromatic LED targets with coupled bandpass filter imaging, is introduced. Then, to examine the measurement accuracy of the proposed advanced video deflectometer in outdoor environments, vertical motions of an LED target with precisely-controlled translations were measured and compared with prescribed values. Finally, by tracking six LED targets mounted on the bridge, the developed video deflectometer was applied for field, remote, and multipoint deflection measurement of the Wuhan Yangtze River Bridge, one of the most prestigious and most publicized constructions in China, during its routine safety evaluation tests. Since the proposed video deflectometer using actively illuminated LED targets offers prominent merits of remote, contactless, real-time, and multipoint deflection measurement with strong robustness against ambient light changes, it has great potential in the routine safety evaluation of various bridges and other large-scale engineering structures.<\/jats:p>","DOI":"10.3390\/s16091344","type":"journal-article","created":{"date-parts":[[2016,8,23]],"date-time":"2016-08-23T10:18:55Z","timestamp":1471947535000},"page":"1344","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":88,"title":["Remote Bridge Deflection Measurement Using an Advanced Video Deflectometer and Actively Illuminated LED Targets"],"prefix":"10.3390","volume":"16","author":[{"given":"Long","family":"Tian","sequence":"first","affiliation":[{"name":"Institute of Solid Mechanics, Beihang University, Beijing 100191, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bing","family":"Pan","sequence":"additional","affiliation":[{"name":"Institute of Solid Mechanics, Beihang University, Beijing 100191, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2016,8,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1680\/istbu.1999.31257","article-title":"Monitoring of structures using the global positioning system","volume":"134","author":"Brown","year":"1999","journal-title":"Struct. Build."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3178","DOI":"10.1016\/j.engstruct.2007.03.012","article-title":"Detecting bridge dynamics with GPS and triaxial accelerometers","volume":"29","author":"Meng","year":"2007","journal-title":"Eng. Struct."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1016\/S0022-460X(03)00202-5","article-title":"Experimental analysis of a high-speed railway bridge under Thalys trains","volume":"268","author":"Xia","year":"2003","journal-title":"J. Sound Vib."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"208","DOI":"10.1016\/j.ndteint.2006.10.007","article-title":"Static and dynamic testing of bridges through microwave interferometry","volume":"40","author":"Pieraccini","year":"2007","journal-title":"NDT E Int."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"182","DOI":"10.1061\/(ASCE)BE.1943-5592.0000334","article-title":"Measuring deflections of a short-span railway bridge using a robotic total station","volume":"18","author":"Psimoulis","year":"2013","journal-title":"J. Bridge Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1016\/0141-0296(93)90054-8","article-title":"Measurements of static and dynamic displacement from visual monitoring of the Humber Bridge","volume":"154","author":"Stephen","year":"1993","journal-title":"Eng. Struct."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/S0263-2241(99)00006-8","article-title":"Investigation of the dynamic characteristic of bridge structures using a computer vision method","volume":"25","author":"Oleszak","year":"1999","journal-title":"Measurement"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"785","DOI":"10.1088\/0964-1726\/12\/5\/016","article-title":"A vision-based approach for the direct measurement of displacements in vibrating systems","volume":"12","author":"Wahbeh","year":"2003","journal-title":"Smart Mater. Struct."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1007\/s11340-006-6124-2","article-title":"Real-time displacement measurement of a flexible bridge using digital image processing techniques","volume":"46","author":"Lee","year":"2006","journal-title":"Exp. Mech."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1111\/j.1747-1567.2006.00132.x","article-title":"Bridge deflection measurement using digital image correlation","volume":"31","author":"Yoneyama","year":"2007","journal-title":"Exp. Tech."},{"key":"ref_11","first-page":"255","article-title":"Vibration monitoring of multiple bridge points by means of a unique vision-based measuring system","volume":"54","author":"Busca","year":"2014","journal-title":"Exp. Tech."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1016\/j.engstruct.2014.04.051","article-title":"Non-contact measurement of the dynamic displacement of railway bridges using an advanced video-based system","volume":"75","author":"Ribeiro","year":"2014","journal-title":"Eng. Struct."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"16557","DOI":"10.3390\/s150716557","article-title":"A vision-based sensor for noncontact structural displacement measurement","volume":"15","author":"Feng","year":"2015","journal-title":"Sensors"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.ndteint.2015.12.006","article-title":"Real-time, non-contact and targetless measurement of vertical deflection of bridges using off-axis digital image correlation","volume":"79","author":"Pan","year":"2016","journal-title":"NDT E Int."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1002\/stc.1547","article-title":"Three-dimensional dynamic deflections and natural frequencies of a stiff footbridge based on measurements of collocated sensors","volume":"21","author":"Moschas","year":"2014","journal-title":"Struct. Control Health Monitor."},{"key":"ref_16","unstructured":"Jung, W., Shin, D., Woo, S., Park, W., and Kim, S. (July, January 29). Hibrid approach of cameras and GPS for displacement measurements of super long-span bridges. Proceedings of the 28th Congress of the International Association for Automation and Robotics in Construction, Seoul, Korea."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Pan, B., Wu, D.F., Wang, Z.Y., and Xia, Y. (2011). High-temperature digital image correlation for full-field deformation measurement at 1200 \u00b0C. Meas. Sci. Technol., 22.","DOI":"10.1088\/0957-0233\/22\/1\/015701"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"204","DOI":"10.1016\/j.optlastec.2011.06.019","article-title":"An active imaging digital image correlation method for deformation measurement insensitive to ambient light","volume":"44","author":"Pan","year":"2012","journal-title":"Opt. Laser Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1277","DOI":"10.1007\/s11340-013-9717-6","article-title":"Fast, robust and accurate digital image correlation calculation without redundant computations","volume":"53","author":"Pan","year":"2013","journal-title":"Exp. Mech."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"285","DOI":"10.2320\/matertrans.I-M2011843","article-title":"Bridge deflection measurement using digital image correlation with camera movement correction","volume":"53","author":"Yoneyama","year":"2012","journal-title":"Mater. Trans."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Yu, L.P., and Pan, B. (2015). The errors in digital image correlation due to overmatched shape functions. Meas. Sci. Technol., 26.","DOI":"10.1088\/0957-0233\/26\/4\/045202"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2915","DOI":"10.1117\/1.1314593","article-title":"Systematic errors in digital image correlation caused by intensity interpolation","volume":"39","author":"Schreier","year":"2000","journal-title":"Opt. Eng."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1161","DOI":"10.1016\/j.optlaseng.2013.04.009","article-title":"Bias error reduction of digital image correlation using Gaussian pre-filtering","volume":"51","author":"Pan","year":"2013","journal-title":"Opt. Lasers Eng."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"248","DOI":"10.1111\/str.12137","article-title":"Experimental analysis of the errors due to polynomial interpolation in digital image correlation","volume":"51","author":"Baldi","year":"2015","journal-title":"Strain"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"7037","DOI":"10.1364\/OE.16.007037","article-title":"Study on subset size selection in digital image correlation for speckle patterns","volume":"16","author":"Pan","year":"2008","journal-title":"Opt. Express"},{"key":"ref_26","unstructured":"Wuhan Yangtze River Bridge. Available online: https:\/\/en.wikipedia.org\/wiki\/Wuhan_Yangtze_River_Bridge."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/9\/1344\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:29:00Z","timestamp":1760210940000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/9\/1344"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,8,23]]},"references-count":26,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2016,9]]}},"alternative-id":["s16091344"],"URL":"https:\/\/doi.org\/10.3390\/s16091344","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,8,23]]}}}