Several approaches to feature definition and extraction have been considered. Choice depends on the camera used, the level of subject cooperation, the throughput required, and the price to be paid.

• 特征定义和提取的一些方法已经得到公认。这些选择取决于所使用摄像机的类型、验证对象的合作程度、系统吞吐量的要求以及所需的花费等。