Journal of the Institute of Electronics Engineers of Korea SP (대한전자공학회논문지SP)

The Institute of Electronics and Information Engineers (대한전자공학회)
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Using Contour Matching for Omnidirectional Camera Calibration

투영곡선의 자동정합을 이용한 전방향 카메라 보정

  • 황용호 (중앙대학교 첨단영상대학원 영상학과) ;
  • 홍현기 (중앙대학교 첨단영상대학원 영상학과)
  • Published : 2008.11.25
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Abstract

Omnidirectional camera system with a wide view angle is widely used in surveillance and robotics areas. In general, most of previous studies on estimating a projection model and the extrinsic parameters from the omnidirectional images assume corresponding points previously established among views. This paper presents a novel omnidirectional camera calibration based on automatic contour matching. In the first place, we estimate the initial parameters including translation and rotations by using the epipolar constraint from the matched feature points. After choosing the interested points adjacent to more than two contours, we establish a precise correspondence among the connected contours by using the initial parameters and the active matching windows. The extrinsic parameters of the omnidirectional camera are estimated minimizing the angular errors of the epipolar plane of endpoints and the inverse projected 3D vectors. Experimental results on synthetic and real images demonstrate that the proposed algorithm obtains more precise camera parameters than the previous method.

감시 및 로보트 분야 등에서 다양하게 사용되는 전방향(omnidirectional) 카메라 시스템은 넓은 시야각을 제공한다. 전방향 카메라의 사영모델과 외부변수를 추정하는 대부분의 기존 연구에서는 사전에 설정된 영상 간의 대응관계를 가정한다. 본 논문에서는 두 장의 전방향 영상으로부터 투영곡선을 자동으로 정합하여 카메라의 외부변수를 추정하는 새로운 알고리즘이 제안된다. 먼저 두 영상에서 대응되는 특징점으로부터 에피폴라 구속조건을 계산하여 초기 카메라 변수를 계산한다. 검출된 특징점과 투영곡선을 대상으로 능동적(active) 정합방법으로 대응관계를 결정한다. 최종 단계에서 대응 투영곡선을 구성하는 양 끝점의 에피폴라(epipolar) 평면과 3차원 벡터의 각도 오차를 최소화하는 카메라 변수를 추정한다. 합성영상과 어안렌즈(fisheye lens)로 취득된 실제 영상을 대상으로 제안된 알고리즘이 기존 방법에 비해 카메라의 외부변수를 정확하게 추정함을 확인하였다.

Keywords

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