Publication detail
Camera calibration method of optical system for large field measurement of hot forgings in heavy industry
HURNÍK, J. ZATOČILOVÁ, A. PALOUŠEK, D.
English title
Camera calibration method of optical system for large field measurement of hot forgings in heavy industry
Type
conference paper
Language
en
Original 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.
English 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.
Keywords in English
camera calibration, large field, forgings, measurement, space resection
Released
21.06.2019
Publisher
SPIE
Location
Munich, Germany
ISBN
9781510627918
ISSN
0277-786X
Book
Optical Measurement Systems for Industrial Inspection XI
Volume
11056
Number
-
Edition number
11056
Pages from–to
1–12
Pages count
12
BIBTEX
@inproceedings{BUT158410,
author="Jakub {Hurník} and Aneta {Zatočilová} and David {Paloušek},
title="Camera calibration method of optical system for large field measurement of hot forgings in heavy industry",
booktitle="Optical Measurement Systems for Industrial Inspection XI",
year="2019",
volume="11056",
number="-",
month="June",
pages="1--12",
publisher="SPIE",
address="Munich, Germany",
isbn="9781510627918",
issn="0277-786X"
}