As we know, photogrammetry methods like structure from motion (SFM) has the potential to generate 3D models or point cloud from 2D imagery data. Combined with UAVs, this method can provide a significant help for civil engineers in rapid modeling. The usage scenario could be urban modeling, post-disaster survey and construction site inspection. To have a better understanding of the limitation of the method and related influence factors, a lab-based experiment has been conducted in UCD.
With the help from my colleagues Iman and Atteyeh, four masonry walls have been built in the lab. Both the Laser scanner and the digital camera have been applied for data collection. An adjustable tripod has used to control the camera angle and distance to the wall. The reconstruction process has been completed by the open source software VisualSFM. After a comparison, we figure out that the result is highly related to the images angles. The data completeness, density distribution and geometry accuracy are all related to the angle selection. More details have presented in the conference paper ‘The effect of angles and distance on image-based, three-dimensional reconstructions’- DOI10.1201/9781315210469-350. The final suggestion is that, in UAV inspection, it is much better to put the camara axis vertical to the target surface. And using muitipal flight path can improving the data completeness.
School of Civil, Structural and Environmental Engineering
University College Dublin, Ireland