Please use this identifier to cite or link to this item: http://hdl.handle.net/11400/5062
Title: Automatic camera calibration for cultural heritage application using unstructured planar objects
Authors: Καλησπεράκης, Ηλίας
Γραμματικόπουλος, Λάζαρος
Καρράς, Γιώργος
Πέτσα, Έλλη
Adam, K.
Item type: Conference publication
Conference Item Type: Full Paper
Keywords: Camera calibration;Point operator;Radial distortion;Bundle adjustment;Automation;Αυτοματισμός;Κάμερα βαθμονόμησης
Subjects: Technology
Photogrammetry
Τεχνολογία
Φωτογραμμετρία
Issue Date: 29-Jan-2015
2-Sep-2013
Date of availability: 29-Jan-2015
Abstract: As a rule, image-based documentation of cultural heritage relies today on ordinary digital cameras and commercial software. As such projects often involve researchers not familiar with photogrammetry, the question of camera calibration is important. Freely available open-source user-friendly software for automatic camera calibration, often based on simple 2D chess-board patterns, are an answer to the demand for simplicity and automation. However, such tools cannot respond to all requirements met in cultural heritage conserva-tion regarding possible imaging distances and focal lengths. Here we investigate the practical possibility of camera calibration from unknown planar objects, i.e. any planar surface with adequate texture; we have focused on the example of urban walls covered with graffiti. Images are connected pair-wise with inter-image homographies, which are estimated automatically through a RANSAC-based approach after extracting and matching interest points with the SIFT operator. All valid points are identified on all images on which they appear. Provided that the image set includes a ‘fronto-parallel’ view, inter-image homographies with this image are regarded as emulations of image-to-world homographies and allow computing initial estimates for the interior and exterior orientation elements. Following this initialization step, the estimates are introduced into a final self-calibrating bundle adjustment. Measures are taken to discard unsuitable images and verify object planarity. Results from practical experimentation indicate that this method may produce satisfactory results. The authors intend to incorporate the described approach into their freely available user-friendly software tool, which relies on chess-boards, to assist non-experts in their projects with image-based approaches.
Description: proceedings
Language: English
Citation: Adam, K., Kalisperakis, I., Grammatikopoulos, L., Karras, I. and Petsa, I. (2013). Automatic camera calibration for cultural heritage application using unstructured planar objects. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XL-5/W2, 2013 XXIV International CIPA Symposium, 2-6/09/2013, Strasbourg, France . Available from: http://cipa.icomos.org/fileadmin/template/doc/STRASBOURG/ARCHIVES/isprsarchives-XL-5-W2-1-2013.pdf
Conference: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, International CIPA Symposium, 2.
Access scheme: Publicly accessible
License: Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ηνωμένες Πολιτείες
URI: http://hdl.handle.net/11400/5062
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