Refractive Structure-from-Motion Through a Flat Refractive Interface

Chadebecq, François; Vasconcelos, Francisco; Dwyer, George; Lacher, Rene; Ourselin, Sébastien; Vercauteren, Tom; Stoyanov, Danail

doi:10.1109/iccv.2017.568

Cited by 25 publications

(12 citation statements)

References 27 publications

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“…Our approach is particularly flexible and can be applied to various applications of underwater imaging and vision behind a thin refractive interface. This paper extends our previous work (Chadebecq et al 2017) by: i. providing with an explicit formulation of the refractive Fundamental relationship (rF), further developing the previous theoretical derivation of the two-view geometry for a fixed refractive plane (Chari and Sturm 2009) (see Sect. 4).…”

Section: Contributionsupporting

confidence: 55%

Refractive Two-View Reconstruction for Underwater 3D Vision

et al. 2019

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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.

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Section: Contributionsupporting

confidence: 55%

Refractive Two-View Reconstruction for Underwater 3D Vision

et al. 2019

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“…Underwater shape reconstruction techniques, such as SfM and multi-view stereo, as well as calibration techniques of camera systems and refractive interface have been widely researched [7,1,10,17,9,6,11,19,5,18]. For calibration, Chari and Sturm defined a geometric model for typical underwater camera setup and derived the projection matrix, the fundamental matrix, and the homogprahy matrix [7].…”

Section: Related Workmentioning

confidence: 99%

“…Shibata et al achieved scalereconstructable SfM by using refraction caused by a planar refractive interface [19]. Most recently, Chadebecq et al considered thick refractive interface for underwater SfM, and derived fundamental matrix [5]. All those underwater SfM papers assume the camera in housing scenario.…”

Section: Related Workmentioning

confidence: 99%

“…We call the scenario "Static interface" if the refractive interface is static relative to the underwater shape, and "Fixed camera" if the camera is static relative to the underwater shape. A case with static refractive interface relative to the camera is already studied in [11,5], and if all components of the system are static, it is impossible to compute desired parameters due to degeneration.…”

Section: Geometric Constraints For Each Scenariomentioning

confidence: 99%

“…1(a), where a single camera moves together with a planar refractive interface attached to the camera, representing a camera in a housing. This setup has been intensively addressed in the literature [11,5]. On the other hand, there are other possible scenarios, which have not been addressed well in the literature, such as single static camera with moving refractive interface ( Fig.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Unified Underwater Structure-from-Motion

Ichimaru

Taguchi

Kawasaki

2019

2019 International Conference on 3D Vision (3DV)

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This paper shows that accurate underwater 3D shape reconstruction is possible using a single camera, observing a target through a refractive interface. We provide unified reconstruction techniques for a variety of scenarios such as single static camera and moving refractive interface, single moving camera and static refractive interface, and single moving camera and moving refractive interface. In our basic setup, we assume that the refractive interface is planar, and simultaneously estimate the unknown transformations of the planar interface and the camera, and the unknown target shape using bundle adjustment. We also extend it to relax the planarity assumption, which enables us to use waves of the refractive interface for the reconstruction task. Experiments with real data show the superiority of our method to existing methods.

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