Akademik Veri Yönetim Sistemi
4th International Conference on Modern and Advanced Research ICMAR 2025, Konya, Türkiye, 6 - 07 Kasım 2025, ss.180, (Özet Bildiri)
Vision-based methods are widely used in structural health monitoring (SHM) due to their advantages such as non-contact measurement capability and low cost. However, atmospheric conditions including humidity, temperature, and pressure cause refraction effects, which result in apparent but unreal motions on the recorded images, leading to significant errors in displacement and frequency estimations. In this study, an experimental approach was developed to minimize the refraction effect observed in video-based measurements. The experimental setup consisted of a spring-pendulum system designed to perform vertical harmonic motion, with a wooden plate mounted to represent a building wall surface. An artificial target was attached to the plate, and a laser beam was directed near this target. The captured video frames were processed using the Template Matching technique to analyze the motion of both the moving target and the fixed laser point. The analysis showed that the laser spot exhibited refractioninduced scattering ranging between –4.23 mm and 4.13 mm, with a standard deviation of 0.67 mm. This scattering magnitude represents a considerable error level for monitoring structural reactions. Moreover, Fast Fourier transform (FFT) analysis of the displacement data revealed that, after refraction correction, the natural frequency of the structure was clearly identified at 1.114 Hz. In contrast, the uncorrected data showed two additional frequency components at 0.13 Hz and 0.23 Hz alongside the true frequency. The results demonstrate that the proposed method effectively reduces refraction-induced noise, providing more accurate estimations of both displacement and frequency in vision-based structural monitoring applications.