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Proceedings Paper

Camera calibration method of optical system for large field measurement of hot forgings in heavy industry
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Paper Abstract

During the manufacturing process of heavy forgings, simple contact measuring techniques are still used to check the dimensions, therefore an optical measuring system is in demand. In this paper, a camera calibration method for the passive measuring system, which is being developed in collaboration with an industrial partner, is proposed. Our approach is based on space resection and works with robust coded targets, which are distributed in the field of view. The coordinates of targets are measured using TRITOP (GOM) measuring system. This solution allows to build a large calibration field, without a need of large calibration objects. The camera calibration works in 2 steps - at first, the intrinsic parameters of the camera, including lens distortion, are calibrated. These parameters are considered as stable, due to the use of special camera covers. Multi-image version of the calibration method and dense field of calibration targets are used. The second step is performed from every image and employs a single-image extrinsic camera parameters calibration method. Only a few coded calibration targets, mounted on stable objects in the scene, are required. The calibration method was tested in industrial conditions. The method showed great results, the average reprojection error was under 0.1 px. The effect of thermally affected zone on the calibration process is discussed.

Paper Details

Date Published: 21 June 2019
PDF: 12 pages
Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 1105635 (21 June 2019); doi: 10.1117/12.2527693
Show Author Affiliations
Jakub Hurník, Brno Univ. of Technology (Czech Republic)
Aneta Zatocilová, Brno Univ. of Technology (Czech Republic)
David Paloušek, Brno Univ. of Technology (Czech Republic)

Published in SPIE Proceedings Vol. 11056:
Optical Measurement Systems for Industrial Inspection XI
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)

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