• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.462-465
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• 2002

This paper deals with the problem of synthesis of stable and optimal grasps with unknown objects by 3-finger hand. Previous robot grasp research has analyzed mainly with either unknown objects 2D by vision sensor or unknown objects, cylindrical or hexahedral objects, 3D. Extending the previous work, in this paper we propose an algorithm to analyze grasp of unknown objects 3D by vision sensor. This is archived by two steps. The first step is to make a 3D geometrical model of unknown objects by stereo matching which is a kind of 3D computer vision technique. The second step is to find the optimal grasping points. In this step, we choose the 3-finger hand because it has the characteristic of multi-finger hand and is easy to modeling. To find the optimal grasping points, genetic algorithm is used and objective function minimizing admissible farce of finger tip applied to the object is formulated. The algorithm is verified by computer simulation by which an optimal grasping points of known objects with different angles are checked.

• 한국정밀공학회지
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• 제19권11호
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• pp.54-64
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• 2002

This paper deals with the problem of synthesis of stable and optimal grasps with unknown objects by 3-finger hand. Previous robot grasp research has mainly analyzed with either unknown objects 2-dimensionally by vision sensor or known objects, such as cylindrical objects, 3-dimensionally. As extending the previous work, in this study we propose an algorithm to analyze grasp of unknown objects 3-dimensionally by using vision sensor. This is archived by two steps. The first step is to make a 3-dimensional geometrical model for unknown objects by using stereo matching. The second step is to find the optimal grasping points. In this step, we choose the 3-finger hand which has the characteristic of multi-finger hand and is easy to model. To find the optimal grasping points, genetic algorithm is employed and objective function minimizes the admissible force of finger tip applied to the objects. The algorithm is verified by computer simulation by which optimal grasping points of known objects with different angle are checked.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.995-996
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• 2008

This paper proposes a algorithm that generate the intermediate scene from the stereo image. This system based on mesh representation method, and segmented objects which ar calculated from triangles the pro proposed algorithm is composed of two steps. One is triangle grouping using gestalt theory, and the other is disparity estimation using average disparity of segmented object. We make an experiment on the proposed algorithm with some stereo images and obtain good quality disparity map for intermediate scenes.

• 제어로봇시스템학회논문지
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• 제17권3호
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• pp.199-205
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• 2011

This paper presents an algorithm capable of detecting free space for the autonomous vehicle navigation. The algorithm consists of two main steps: 1) estimation of longitudinal profile of road, 2) detection of free space. The estimation of longitudinal profile of road is detection of v-line in v-disparity image which is corresponded to road slope, using v-disparity image and hough transform, Dijkstra algorithm. To detect free space, we detect u-line in u-disparity image which is a boundary line between free space and obstacle's region, using u-disparity image and dynamic programming. Free space is decided by detected v-line and u-line. The proposed algorithm is proven to be successful through experiments under various traffic scenarios.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.437-438
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• 2006

Virtual view synthesis is essential for 3DTV systems, which utilizes the motion parallax cue. In this paper, we propose a multi-step view synthesis algorithm to efficiently reconstruct an arbitrary view from limited number of known views of a 3D scene. We describe an efficient image rectification procedure which guarantees that an interpolation process produce valid views. This rectification method can deal with all possible camera motions. The idea consists of using a polar parameterization of the image around the epipole. Then, to generate intermediate views, we use an efficient dense disparity estimation algorithm considering features of stereo image pairs. Main concepts of the algorithm are based on the region dividing bidirectional pixel matching. The estimated disparities are used to synthesize intermediate view of stereo images. We use computer simulation to show the result of the proposed algorithm.

• 정보처리학회논문지B
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• 제12B권7호
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• pp.767-774
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• 2005

본 논문에서는 스테레오 동영상에서 스네이크를 이용한 객체 윤곽 추적 알고리즘을 제안한다. 제안하는 방법은 두 단계로 구성된다. 첫 번째 단계는 변이 공간에서 스네이크 포인트의 3-D 동작 정보로부터 후보 스네이크 포인트의 위치를 계산하고, 두 번째 단계는 새로 정의한 스네이크에너지 함수를 후보 스네이크 포인트에 적용하여 객체의 윤곽을 추적한다. 제안한 방법은 복잡한 배경을 갖는 영상에서 국부 최소값에 빠지는 문제점과 관심객체의 오목한 윤곽에서 스네이크 포인트가 잘 수렴되지 않는 문제점을 해결 할 수 있었고 실험을 통해 성능을 분석하였다.

• IEIE Transactions on Smart Processing and Computing
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• 제1권3호
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• pp.161-170
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• 2012

This paper presents an efficient and robust approach for determining the correspondence between unbalanced stereo images. The disparity vectors were used instead of feature points, such as corners, to calculate a correspondence relationship. For a faster and optimal estimation, the vectors were classified into several regions, and the homography of each region was calculated using the RANSAC algorithm. The correspondence image was calculated from the images transformed by each homography. Although it provided good results under normal conditions, it was difficult to obtain reliable results in an unbalanced stereo pair. Therefore, a balancing method is also proposed to minimize the unbalance effects using the histogram specification and structural similarity index. The experimental results showed that the proposed approach outperformed the baseline algorithms with respect to the speed and peak-signal-to-noise ratio. This work can be applied to practical fields including 3D depth map acquisition, fast stereo coding, 2D-to-3D conversion, etc.

• Journal of Mechanical Science and Technology
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• 제17권10호
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• pp.1411-1422
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• 2003

The detection of free spaces between obstacles in a scene is a prerequisite for navigation of a mobile robot. Especially for stereo vision-based navigation, the problem of correspondence between two images is well known to be of crucial importance. This paper describes multi-range approach of area-based stereo matching for grid mapping and visual navigation in uncertain environment. Camera calibration parameters are optimized by evolutionary algorithm for successful stereo matching. To obtain reliable disparity information from both images, stereo images are to be decomposed into three pairs of images with different resolution based on measurement of disparities. The advantage of multi-range approach is that we can get more reliable disparity in each defined range because disparities from high resolution image are used for farther object a while disparities from low resolution images are used for close objects. The reliable disparity map is combined through post-processing for rejecting incorrect disparity information from each disparity map. The real distance from a disparity image is converted into an occupancy grid representation of a mobile robot. We have investigated the possibility of multi-range approach for the detection of obstacles and visual mapping through various experiments.

• 한국정밀공학회지
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• 제19권5호
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• pp.36-42
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• 2002

This paper presents the way of building an occupancy grid map which a mobile robot needs to autonomously navigate in the unknown environment. A disparity map resulting from stereo matching can be converted into the 2D distance information. If the stereo matching has some errors, however, the subsequent map becomes unreliable. In this paper, a new morphological filter is proposed to reject 'spikes' of the disparity map due to stereo mismatch by considering the fact that these spikes occur locally. The new method has advantages that it is simpler and more easily realized than existing similar algorithms. Several occupancy grid maps based on stereo vision using the proposed algorithm have been built and compared with the actual distance information to verify the validity of the proposed method.

• 한국음향학회지
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• 제18권2호
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• pp.66-76
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• 1999

본 논문은 스테레오 카메라를 대응점 문제가 발생하지 않을 만큼 병진 및 전진 이동시켜 고속으로 양안 시차 정보를 획득할 수 있다는 것을 제안한다. 병진 이동하는 스테레오 비전에 있어서 오차가 없고 신뢰성이 높은 시차 정보를 획득할 수 있다는 것과 전진 이동하는 스테레오 비전에 있어서는 통상의 스테레오 비전으로는 검출할 수 없는 수평성분을 획득할 수 있다는 것을 나타낸다. 또한 좌우 화상사이의 대응을 미리 한정하기 때문에 한정하지 않을 때에 비해 대응점이 밝고 작게 되므로 고속으로 스테레오 비전을 행할 수 있다. 그러나 전진 이동하는 스테레오 비전에 있어서 화상중심 부근과 폐색영역이 일치하면 바른 양안 시차 정보를 얻을 수 없는 문제가 있다.