Abstract: Based on the imaging feature of SOP components,in order to limit the number of the target area,reduce the computing element angle computation,adopting the algorithm of minimum enclosing rectangle to quickly gain the center coordinates,the approximate area and the approximate perimeter of the target areas,searching out the destination rectangle and calculate the actual center element based on rectangular area and perimeter constraints.Then searching out the single target in the center of the rectangle based on adjacency matrix search algorithm.Finally calculated the center of elements by least squares fitting line .The method is simple and efficient,effectively reduce the computational complexity in the process of element identification.The experimental results show that the algorithm is to ensure high precision positioning for SOP,and at the same time,it can realize high efficiency of component placement.

Key words: minimum enclosing rectangle, Graham algorithm, adjacency matrix, least square method