：给出了一种提取特征点的新方法和合理的特征不变量。该方法根据三角不等式原理利用第三边与另

外两边之和的比值大小来确定角点，以特征点和它相邻的两个特征点所形成的两条直线的夹角正切值以及三角形

第三边与另两边和的比值作为特征不变量。这种特征提取的方法简单，并且由于扩大了模板取值范围，使识别效果受特征点漏检的影响较小。实验表明，该方法不仅简便，而且效果良好。-: In this paper, a new feature point extraction method and the characteristics of rational invariants. The method is based on the principle of triangle inequality with the use of the third side and both sides of the ratio of the size to determine the Corner to feature point and its two adjacent feature points formed by the angle between two tangent linear and the third triangle on both sides and edges with another feature of the ratio as a variable. This feature extraction method is simple, and as a result of the expansion of the scope of the template values to identify the effect of feature points by the impact of smaller undetected. Experiments show that the method is not only simple, but effective.