the classical basis of the linked group are given which is used to recognize the engineering drawing papers, and the direction determination algorithm for the character string is also described.
文中关于连通群的理论分析为解决工程图中字符、数字和图形的正确分割、分类及排除噪声的干扰提供了依据,连通群的迭代算法可準确定位字符串的方向。