3D Measurement and Feature Extraction for Metal Nuts.

The metal nuts used to assemble bridges and buildings inevitably deteriorate over time, which makes it crucial to obtain various parameters related to their conditions during maintenance activities and then determine whether and when they should be replaced. However, since measuring the essential parameters such as height and minimum width of large numbers of nuts is a very time- and energy-consuming project, we developed a method that uses a laser measurement instrument to collect three-dimensional (3D) information on such nuts. We then combined it with a software application that can quickly and automatically calculate their 3D point cloud data and obtain their parameters. As a result, building and bridge inspections can now be conducted more quickly and efficiently, and with reduced manpower requirements.