The Influence of Autofocus Lenses in the Camera Calibration Process

[EN] Camera calibration is a crucial step in robotics and computer vision. Accurate camera parameters are necessary to achieve robust applications. Nowadays, camera calibration process consists of adjusting a set of data to a pin-hole model, assuming that with a reprojection error close to zero, cam...

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Detalhes bibliográficos
Autores: Ricolfe Viala, Carlos|||0000-0002-2980-4569, Esparza Peidro, Alicia|||0000-0002-7471-8686
Formato: artículo
Fecha de publicación:2021
País:España
Recursos:Universitat Politècnica de València (UPV)
Repositorio:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
Idioma:inglés
OAI Identifier:oai:riunet.upv.es:10251/189894
Acesso em linha:https://riunet.upv.es/handle/10251/189894
Access Level:acceso abierto
Palavra-chave:2-D calibration template
Autofocus lenses
Camera calibration
Camera parameters coupling
INGENIERIA DE SISTEMAS Y AUTOMATICA
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oai_identifier_str oai:riunet.upv.es:10251/189894
network_acronym_str ES
network_name_str España
repository_id_str
spelling The Influence of Autofocus Lenses in the Camera Calibration ProcessRicolfe Viala, Carlos|||0000-0002-2980-4569Esparza Peidro, Alicia|||0000-0002-7471-86862-D calibration templateAutofocus lensesCamera calibrationCamera parameters couplingINGENIERIA DE SISTEMAS Y AUTOMATICA[EN] Camera calibration is a crucial step in robotics and computer vision. Accurate camera parameters are necessary to achieve robust applications. Nowadays, camera calibration process consists of adjusting a set of data to a pin-hole model, assuming that with a reprojection error close to zero, camera parameters are correct. Since all camera parameters are unknown, computed results are considered true. However, the pin-hole model does not represent the camera behavior accurately if the autofocus is considered. Real cameras with autofocus lenses change the focal length slightly to obtain sharp objects in the image, and this feature skews the calibration result if a unique pin-hole model is computed with a constant focal length. In this article, a deep analysis of the camera calibration process is done to detect and strengthen its weaknesses when autofocus lenses are used. To demonstrate that significant errors exist in computed extrinsic parameters, the camera is mounted in a robot arm to know true extrinsic camera parameters with an accuracy under 1 mm. It is also demonstrated that errors in extrinsic camera parameters are compensated with bias in intrinsic camera parameters. Since significant errors exist with autofocus lenses, a modification of the widely accepted camera calibration method using images of a planar template is presented. A pin-hole model with distance-dependent focal length is proposed to improve the calibration process substantially.Institute of Electrical and Electronics EngineersDepartamento de Ingeniería de Sistemas y AutomáticaEscuela Técnica Superior de Ingeniería Aeroespacial y Diseño IndustrialInstituto Universitario de Automática e Informática IndustrialEscuela Técnica Superior de Ingeniería IndustrialRepositorio Institucional de la Universitat Politècnica de València Riunet20212021-02-02journal articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfapplication/pdfhttps://riunet.upv.es/handle/10251/189894reponame:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valénciainstname:Universitat Politècnica de València (UPV)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2Reserva de todos los derechoshttp://rightsstatements.org/vocab/InC/1.0/info:eu-repo/semantics/openAccessoai:riunet.upv.es:10251/1898942026-06-13T07:49:27Z
dc.title.none.fl_str_mv The Influence of Autofocus Lenses in the Camera Calibration Process
title The Influence of Autofocus Lenses in the Camera Calibration Process
spellingShingle The Influence of Autofocus Lenses in the Camera Calibration Process
Ricolfe Viala, Carlos|||0000-0002-2980-4569
2-D calibration template
Autofocus lenses
Camera calibration
Camera parameters coupling
INGENIERIA DE SISTEMAS Y AUTOMATICA
title_short The Influence of Autofocus Lenses in the Camera Calibration Process
title_full The Influence of Autofocus Lenses in the Camera Calibration Process
title_fullStr The Influence of Autofocus Lenses in the Camera Calibration Process
title_full_unstemmed The Influence of Autofocus Lenses in the Camera Calibration Process
title_sort The Influence of Autofocus Lenses in the Camera Calibration Process
dc.creator.none.fl_str_mv Ricolfe Viala, Carlos|||0000-0002-2980-4569
Esparza Peidro, Alicia|||0000-0002-7471-8686
author Ricolfe Viala, Carlos|||0000-0002-2980-4569
author_facet Ricolfe Viala, Carlos|||0000-0002-2980-4569
Esparza Peidro, Alicia|||0000-0002-7471-8686
author_role author
author2 Esparza Peidro, Alicia|||0000-0002-7471-8686
author2_role author
dc.contributor.none.fl_str_mv Departamento de Ingeniería de Sistemas y Automática
Escuela Técnica Superior de Ingeniería Aeroespacial y Diseño Industrial
Instituto Universitario de Automática e Informática Industrial
Escuela Técnica Superior de Ingeniería Industrial
Repositorio Institucional de la Universitat Politècnica de València Riunet
dc.subject.none.fl_str_mv 2-D calibration template
Autofocus lenses
Camera calibration
Camera parameters coupling
INGENIERIA DE SISTEMAS Y AUTOMATICA
topic 2-D calibration template
Autofocus lenses
Camera calibration
Camera parameters coupling
INGENIERIA DE SISTEMAS Y AUTOMATICA
description [EN] Camera calibration is a crucial step in robotics and computer vision. Accurate camera parameters are necessary to achieve robust applications. Nowadays, camera calibration process consists of adjusting a set of data to a pin-hole model, assuming that with a reprojection error close to zero, camera parameters are correct. Since all camera parameters are unknown, computed results are considered true. However, the pin-hole model does not represent the camera behavior accurately if the autofocus is considered. Real cameras with autofocus lenses change the focal length slightly to obtain sharp objects in the image, and this feature skews the calibration result if a unique pin-hole model is computed with a constant focal length. In this article, a deep analysis of the camera calibration process is done to detect and strengthen its weaknesses when autofocus lenses are used. To demonstrate that significant errors exist in computed extrinsic parameters, the camera is mounted in a robot arm to know true extrinsic camera parameters with an accuracy under 1 mm. It is also demonstrated that errors in extrinsic camera parameters are compensated with bias in intrinsic camera parameters. Since significant errors exist with autofocus lenses, a modification of the widely accepted camera calibration method using images of a planar template is presented. A pin-hole model with distance-dependent focal length is proposed to improve the calibration process substantially.
publishDate 2021
dc.date.none.fl_str_mv 2021
2021-02-02
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://riunet.upv.es/handle/10251/189894
url https://riunet.upv.es/handle/10251/189894
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Reserva de todos los derechos
http://rightsstatements.org/vocab/InC/1.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Reserva de todos los derechos
http://rightsstatements.org/vocab/InC/1.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Institute of Electrical and Electronics Engineers
publisher.none.fl_str_mv Institute of Electrical and Electronics Engineers
dc.source.none.fl_str_mv reponame:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
instname:Universitat Politècnica de València (UPV)
instname_str Universitat Politècnica de València (UPV)
reponame_str RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
collection RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,198674

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