Research Of Image Matching Based On Oriented Point And Oriented Line Segment

Image matching is one of crucial techniques in the Integrated Circuit (IC)manufacturing equipments. As IC fabrication and packaging tend to be smaller, highlyintegrated, three-dimensional and massive, the vision based high precision alignmentsub-system is indispensable. However, the traditional area based image matching methodsare computationally expensive and sensitive to illumination changes. For the purpose ofimproving the performance of the alignment sub-system, the dissertation investigates theimage matching methods based on oriented point and oriented line segment systematically.And we develop a program for matching images fast and accurately using C++. The maincontributions are as follows:1) The coordinates and the gradient direction of an edge point are used to describe anew geometric feature named oriented point. And similarly, The coordinates ofendpoints and the gradient direction of a line segment are used to describe anothernew geometric feature named oriented line segment. A geometric denoisingmethod is proposed to make the oriented point more stable and to eliminate theinfluence of outliers on the oriented line segment.2) A robust similarity measure is defined by using the pixel level oriented points.During the search for transformation parameters, methods based on similaritymeasure threshold and image pyramids are used for computational efficiency. Amethod based on mask is proposed to avoid exhaustive search in the highest levelof image pyramid, where a mask is built according to the oriented points in thetarget image. The oriented point based image matching algorithm is able toquickly achieve coarse matching between images.3) A new objective function is built by using the subpixel level oriented points,which contains shearing matrix and scaling matrix. Also, the point to line error measure is used for better accuracy. However, the new objective function isnonlinear equation and this optimization problem is very time consuming. Toobtain the closed-form solution efficiently, the point to line error is equivalentlycomputed as the point to line error. The minimum point to line error based imagematching algorithm is able to quickly achieve fine matching between images.4) A Point-Line Duality (PLD) based method is proposed for image matching byusing the oriented line segments as feature. According to the fact that a linesegment in the image (x-y) space corresponds to a point in the dual (-) space,the line matching problem is converted to a point matching problem. For thepurpose of matching stability and computational efficiency, a point mergingalgorithm is proposed to deal with the fragmentary line segments that shouldbelong to a single line. A point pattern matching algorithm is proposed todetermine the transformation parameters, and the matched line pairs can also bereadily determined. The PLD image matching algorithm is able to quickly achievecoarse matching between images.