scale invariant feature

• 尺度不变特征

scale invariant feature的用法和样例：

例句

1. The convex hulls were extracted from the feature points of the reference and test images, and then the affine invariants were calculated.
   该方法利用从参考图和测试图中得到的特征点提取其凸壳，并计算凸壳的仿射不变特征向量。