Development of a vision based deflection measurement system and its accuracy assessment

A vision-based method for measuring civil engineering constructions’ in-plane deflection is presented in this paper. Displacements of points are computed by means of digital image correlation. The application of homography mapping enables the deflection field to be computed from two images of the structure acquired from two different points in space. The verification of the developed system is performed using the coordinate measuring technique. Results of the beam deflection obtained from the developed vision system and Laser Tracker device are compared. Moreover, the uncertainty of the system is evaluated and possibilities for its improvement discussed.

► Correctness of developed vision-based system (VS) was proven on the basis of comparison with Laser Tracker (LT).
► The mean percentage error of VS and LT results comparison amounted to 1.11%.
► Applied rectification algorithm does not affect accuracy of measurement (0.003 mm regarding standard uncertainty).
► Developed system enables structure static and quasi-static states assessments.