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Fast Ellipse Detection based on Three Point Algorithm with Edge Angle Information
강동중,권배근,Zhu Teng,노태정 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.3
In this paper, we introduce a fast ellipse detection method that uses the geometric properties of threepoints on an ellipse. Many conventional ellipse detection methods carry out detection using five points, but arandom selection of such points among candidate edges requires much redundant processing. To search for anellipse with the minimum number of points, this study used the normal and differential equations of an ellipse,which requires three points based on their locations and edge angles. First, to reduce the number of candidateedges, the edges were divided into 8 groups depending on the edge angle, and then a new geometric constraintcalled the quadrant condition was introduced to reduce noisy candidate edges. Clustering was employed to findprominent candidates in the space of a few ellipse parameters. Experiments using many real images showed thatthe proposed method satisfies both reliability and computing speed for ellipse detection.
이차원 4링크 기구의 다중 간극들의 영향을 줄이기 위한 코일 스프링의 설계
강동중,이학수,윤용산 대한기계학회 1990 대한기계학회논문집 Vol.14 No.6
본 연구에서는 다간극기구의 간극의 영향을 제거하기 위해 코일스프링의 사용 을 대안으로 제시하였다. A systematic method of design modification to reduce the influence of impact from multiple clearances in a planar four bar mechanism is developed. For this purpose, an optimization method is used with the objective function which is the linear sum of the Earles and Wu criteria for every joints with clearances. One coil spring is attached to a joint of limited range of revolution to reduce the undesirable dynamic effects due to clearances at joints. The stiffness of the coil spring and its pre-loading angle are chosen as design variables. A numerical example is taken for a four bar mechanism. The initial and modified mechanisms are compared using a clearance mechanism analysis technic to see the difference in dynamic effects due to contact loss. It is found that the modified mechanism produces much more smooth joint contact forces than the original design.
전탐색 회피에 의한 고속 에지기반 점 상관 알고리즘의 개발
강동중,김문조,김민성,이응주 한국정보처리학회 2004 정보처리학회논문지. 소프트웨어 및 데이터 공학 Vol.11 No.3
일반적인 공장환경에서 적용할 수 있는 비젼 검사시스템의 개발을 위해서는 안정적이면서도 고속 패턴정합을 수행하는 알고리즘의 개발이 필요하다. 본 논문에서는 전탐색 회피기법을 이용하는 자동화용 패턴검사를 위한 에지 기반의 점상관 고속 알고리즘을 제안한다. 이 알고리즘은 탐색할 영상의 에지특성을 분석함에 의해 전탐색을 회피함으로써 탐색복잡도를 크게 개선한다. 농담정규화정합(NGC)법을 사용하는 통상적인 검사 알고리즘은 공장환경에 적용할 때 몇가지 문제점을 극복해야 한다. 첫 번째는 과도한 계산량으로 고속동작을 가능하게 하기 위해 특별한 알고리즘의 설계가 필요하며 고속 하드웨어의 사용을 요구한다. 두 번째는 불안정한 조명조건 하에서도 신뢰성 있는 검사결과를 주어야 한다는 것이다. 전통적인 NGC 알고리즘은 조명의 불안정에 따라 검사결과가 크게 변동하는 특성을 가지고 있다. 본 논문에서는 이러한 단점을 극복하기 위해 에지 기반의 점상관 알고리즘을 제안한다. 계산량을 개선하기 위해 전탐색 회피 알고리즘을 개발하여 적용하고, 에지 피라미드 구조를 탐색에 도입하여 실시간에 근접하는 시간 복잡도를 달성한다. 제안된 방법들은 실제 영상에 적용하여 신뢰성을 검증한다. For visual inspection system in real industrial environment, it is one of most important tasks to design fast and stable pattern matching algorithm. This paper presents an edge-based point correlation algorithm avoiding full search in visual inspection system. Conventional algorithms based on NGC(normalized gray-level correlation) have to overcome some difficulties for applying to automated inspection system in factory environment. First of all, NGC algorithms need high time complexity and thus high performance hardware to satisfy real-time process. In addition, lighting condition in realistic factory environments is not stable and therefore intensity variation from uncontrolled lights gives many troubles for applying directly NGC as pattern matching algorithm. In this paper, we propose an algorithm to solve these problems from using thinned and binarized edge data and skipping full point search with edge-map analysis. A point correlation algorithm with the thinned edges is introduced with image pyramid technique to reduce the time complexity. Matching edges instead of using original gray-level pixel data overcomes NGC problems and pyramid of edges also provides fast and stable processing. All proposed methods are proved from experiments using real images.
강동중 동명정보대학교 2000 東明情報大學校論文集 Vol.3 No.-
We propose a dynamic programming-based formulation for recognizing and matching line patterns by defining a robust and stable geometric representation that is based on the perceptual organizations. Usually, the endpoint proximity and co-linearity of image lines, as two main perceptual organization groups, are useful cues to match the model shape in the scene. As the endpoint proximity, we detect junctions from image lines. We then search for junction groups by using geometric constraint between the junctions, which has a geometric invariant property. A junction chain similar to the model chain is searched in the scene, based on a local comparison. A Dynamic Programming-based search algorithm reduces the time complexity for the search of the model chain in the scene. Our system can find a reasonable matching, although there exist severly distorted objects in the scene. We demonstrate the feasibility of the DP-based matching method using both synthetic and real images.