Exploiting Image Assisted Total Station in Digital Image Correlation (DIC) displacement measurements: insights from laboratory experiments

Abstract

The paper addresses a relevant subject in structural health monitoring for civil engineering applications such as bridges or other large structures. Experimental laboratory program on the accuracy and precision of remote displacement measurements was reported. Could an onboard optical camera of a Total Station (Image-Assisted Total Station (IATS) Leica Nova) be exploited to integrate other measurement techniques or even temporarily replace ordinary instrumental observations in case of instrument failure? The experimental campaign was carried out in the Institute of Engineering Geodesy and Measurement Systems Laboratory at Graz University of Technology (Austria). In particular, pictures of a predetermined moving target, acquired from the IATS’ onboard optical camera (focal length of 231 mm), have been processed through Digital Image Correlation (DIC) to get displacements measures. The obtained results were validated using the “ground truth” assessed by the laboratory equipment. The same was done, capturing pictures with a Digital Single-Lens Reflex (DSLR) consumer camera (focal length of 55 and 85 mm) and using the same experimental setup. Once validated, a comparison between IATS’ optical camera and DSLR observations returned very similar accuracy and precision. The experimental outcomes suggest that comparable results can be achieved by processing pictures from both IATS’ onboard camera.

Keywords

• digital image correlation (dic)
• digital single-lens reflex (dslr)
• image-assisted total station (iats)
• measurement
• displacement
• optical sensors