Authors:
Kosuke Takahashi
;
Dan Mikami
;
Mariko Isogawa
and
Akira Kojima
Affiliation:
Nippon Telegraph and Telephone Corporation, Japan
Keyword(s):
Camera Calibration, Cornea Reflection, Spherical Mirror.
Related
Ontology
Subjects/Areas/Topics:
Computer Vision, Visualization and Computer Graphics
;
Device Calibration, Characterization and Modeling
;
Image Formation and Preprocessing
Abstract:
In this paper, we propose a novel method to extrinsically calibrate a camera to a 3D reference object that is not directly visible from the camera. We use the spherical human cornea as a mirror and calibrate the extrinsic parameters from the reflections of the reference points. The main contribution of this paper is to present a cornea-reflection-based calibration algorithm with minimal configuration; there are five reference points on a single plane and one mirror pose. In this paper, we derive a linear equation and obtain a closed-form solution of extrinsic calibration by introducing two key ideas. The first is to model the cornea as a virtual sphere, which enables us to estimate the center of the cornea sphere from its projection. The second idea is to use basis vectors to represent the position of the reference points, which enables us to deal with 3D information of reference points compactly. Besides, in order to make our method robust to observation noise, we minimize the repro
jection error while maintaining the valid 3D geometry of the solution based on the derived linear equation. We demonstrate the advantages of the proposed method with qualitative and quantitative evaluations using synthesized and real data.
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