PSI - Issue 54

Francisco Afonso et al. / Procedia Structural Integrity 54 (2024) 553–560 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3. Software's functioning logic

5. Field experiments Several trials were conducted to test the system in different settings and configurations, in particular, it was important to adjust various factors in order to improve the final point cloud, such as the exposition time, aperture and gain. It was also important to understand the effect of other parameters and limitations , such as the system’s velocity and any tridimensional reconstruction limitations that can arise from using the developed system and method. After a trial was conducted, the obtained images were converted to the TIFF format and then, together with a CSV document containing the GPS coordinates of the captured images, were used for post-processing with Pix4Dmapper software to reconstruct the point clouds. To this end, many tests were conducted in a laboratorial setting and also inside a moving car. In Fig. 4, a result can be observed from such a trial involving a moving car, where a good level of detail was obtained. After those initial trials, a final experiment was conducted using a moving locomotive and an external GPS module to acquire the GPS coordinates. The employed acquisition parameters were an exposure time of 0.02 ms, aperture f/4 without gain. The final point cloud can be seen in Fig. 5 and Fig. 6, where a good level of detail was obtained.