Monitoring the thermal deformation of steel beams via vision metrology
The multi-epoch deformation monitoring of a series of super-hot steel beams by digital close-range photogrammetry is reported. An on-line configuration of three CCD cameras was established to measure both stable reference points and targets subject to positional displacement. Measurements for each beam were conducted at 7080 epochs over 2 h as the steel cooled from 1100C to near room temperature. Special targeting was required to accommodate the changing colour of the beams from white-hot to brown as they cooled and ensure target survival through a large temperature range. A computational approach was employed whereby the photogrammetric triangulation process for any given recording epoch utilised all images obtained up until that time. The paper discusses all aspects of the project in which seven beams were monitored to a dimensional tolerance of close to 1 mm (RMS 1-sigma).
vision metrology deformation measurement multi-epoch data processing automated image measurement