eprintid: 10087819 rev_number: 31 eprint_status: archive userid: 608 dir: disk0/10/08/78/19 datestamp: 2019-12-13 11:02:31 lastmod: 2021-09-17 22:23:51 status_changed: 2020-06-10 11:09:23 type: article metadata_visibility: show creators_name: Chadebecq, F creators_name: Vasconcelos, F creators_name: Lacher, R creators_name: Maneas, E creators_name: Desjardins, A creators_name: Ourselin, S creators_name: Vercauteren, T creators_name: Stoyanov, D title: Refractive Two-View Reconstruction for Underwater 3D Vision ispublished: pub divisions: UCL divisions: B04 divisions: C05 divisions: F48 divisions: F42 keywords: Underwater imaging · Two-view Refractive Structure-from-Motion · Flat refractive geometry note: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. abstract: Recovering 3D geometry from cameras in underwater applications involves the Refractive Structure-from-Motion problem where the non-linear distortion of light induced by a change of medium density invalidates the single viewpoint assumption. The pinhole-plus-distortion camera projection model suffers from a systematic geometric bias since refractive distortion depends on object distance. This leads to inaccurate camera pose and 3D shape estimation. To account for refraction, it is possible to use the axial camera model or to explicitly consider one or multiple parallel refractive interfaces whose orientations and positions with respect to the camera can be calibrated. Although it has been demonstrated that the refractive camera model is well-suited for underwater imaging, Refractive Structure-from-Motion remains particularly difficult to use in practice when considering the seldom studied case of a camera with a flat refractive interface. Our method applies to the case of underwater imaging systems whose entrance lens is in direct contact with the external medium. By adopting the refractive camera model, we provide a succinct derivation and expression for the refractive fundamental matrix and use this as the basis for a novel twoview reconstruction method for underwater imaging. For validation we use synthetic data to show the numerical properties of our method and we provide results on real data to demonstrate its practical application within laboratory settings and for medical applications in fluid-immersed endoscopy. We demonstrate our approach outperforms classic two-view Structurefrom-Motion method relying on the pinhole-plus-distortion camera model. date: 2020 date_type: published official_url: https://doi.org/10.1007/s11263-019-01218-9 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1728250 doi: 10.1007/s11263-019-01218-9 lyricists_name: Chadebecq, Francois lyricists_name: Desjardins, Adrien lyricists_name: Lacher, Rene lyricists_name: Maneas, Efthymios lyricists_name: Porto Guerra E Vasconcelos, Francisco lyricists_name: Stoyanov, Danail lyricists_name: Vercauteren, Tom lyricists_id: FCHAD50 lyricists_id: AEDES16 lyricists_id: RMLAC65 lyricists_id: EMANE14 lyricists_id: FVASC02 lyricists_id: DSTOY26 lyricists_id: TVERC65 actors_name: Flynn, Bernadette actors_id: BFFLY94 actors_role: owner full_text_status: public publication: International Journal of Computer Vision volume: 128 pagerange: 1101-1117 citation: Chadebecq, F; Vasconcelos, F; Lacher, R; Maneas, E; Desjardins, A; Ourselin, S; Vercauteren, T; Chadebecq, F; Vasconcelos, F; Lacher, R; Maneas, E; Desjardins, A; Ourselin, S; Vercauteren, T; Stoyanov, D; - view fewer <#> (2020) Refractive Two-View Reconstruction for Underwater 3D Vision. International Journal of Computer Vision , 128 pp. 1101-1117. 10.1007/s11263-019-01218-9 <https://doi.org/10.1007/s11263-019-01218-9>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10087819/8/Chadebecq_2020_Article_RefractiveTwo-ViewReconstructi.pdf