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 configuratio n of three CCD cameras was established to measure both stable reference poi nts and targets subject to positional displacement. Measurements for each b eam were conducted at 70-80 epochs over 2 h as the steel cooled from 1100 d egreesC to near room temperature. Special targeting was required to accommo date the changing colour of the beams from white-hot to brown as they coole d and ensure target survival through a large temperature range. A computati onal approach was employed whereby the photogrammetric triangulation proces s for any given recording epoch utilised an images obtained up until that l ime. The paper discusses all aspects of the project in which seven beams we re monitored to a dimensional tolerance of close to 1 mm (RMS 1-sigma). (C) 2000 Elsevier Science B.V. All rights reserved.