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

The Institute of Electronics and Information Engineers (대한전자공학회)
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Image Stabilization Algorithm for Close Watching UAV(Unmanned Aerial Vehicle) Aystem

근접감시용 무인항공기 시스템을 위한 영상 안정화 알고리즘

  • Lee, Hong-Suk (Department of Mechatronics Engineering, Chungnam National University) ;
  • Lee, Tae-Yeoung (Department of Mechatronics Engineering, Chungnam National University) ;
  • Kim, Byoung-Soo (Department of Aerospace Engineering, Chungnam National University) ;
  • Ko, Yun-Ho (Department of Mechatronics Engineering, Chungnam National University)
  • 이홍석 (충남대학교 메카트로닉스공학과) ;
  • 이태영 (충남대학교 메카트로닉스공학과) ;
  • 김병수 (충남대학교 항공우주공학과) ;
  • 고윤호 (충남대학교 메카트로닉스공학과)
  • Received : 2010.03.16
  • Published : 2010.11.25
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Abstract

This paper proposes an image stabilization algorithm for close watching UAV(Unmanned Aerial Vehicle) using motion separation and stabilization mode. The motion of UAV is composed of its actual navigating motion and unwanted vibrating motion so that image sequences obtained from UAV are shaken randomly. In order to stabilize these images we separate the vibrating motion component from UAV motion and remove the effect caused by it from image sequences. In the proposed algorithm the motion and global intensity change of two consecutive images are modeled with 6 motion parameters and 2 intensity change parameters respectively. These modeled parameters are estimated by non-linear least square method based on Gauss-Newton algorithm. The vibrating motion component is separated from the estimated motion using IIR filtering and the geometric deformation caused by it is removed from image sequences. In order to apply the proposed method to real aerial image sequences with many abrupt changes of camera view, we proposed a stabilizing method using two different modes named as stabilizing and non-stabilizing mode. Experimental results show that the accuracy of motion estimation is 99% and the efficiency of removing the vibrating motion component is 90%. We apply the proposed method to real aerial image sequences and verified its stabilizing performance.

본 논문에서는 움직임 분리와 안정화 모드를 이용하여 근접감시용 무인항공기의 영상을 안정화 시키는 알고리즘을 제안하였다. 무인 항공기에서 촬영된 영상에는 임무에 의한 움직임과 기체의 진동에 의한 움직임이 혼합되어 나타난다. 영상을 안정화하기 위해서는 진동에 의한 움직임을 제거하여야 한다. 제안된 알고리즘에서는 연속된 두 영상의 전역움직임을 6계수 움직임 모형과 2계수 밝기변화 모형으로 모델링하고 Gauss-Newton 알고리즘에 기반한 비선형 최소 제곱법(non-linear least squares)을 이용하여 움직임을 추정하였다. 추정된 움직임에서 IIR 필터를 이용하여 진동에 의한 움직임을 분리하여 제거함으로서 영상을 안정화 하였다. 또한 안정화 영상 생성시 시점의 변화가 많은 실제 무인항공영상에 적용하기 위하여 초기화 상태와 안정화 상태의 두 가지의 상태를 가지는 안정화 모드를 제안하였다. 실험결과 99%의 정확도로 전역 움직임을 추정하였고, 90%의 진동에 의한 움직임 제거 성능을 보였다. 또한, 제안한 알고리즘을 실제 항공영상에 적용하여 영상이 안정화 되는 것을 확인하였다.

Keywords

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