Further more, Human faces have large variation in shape at different time Many influences, such a slighting, background, facial expression sand facial details, will easily affect the recognize result.

• 又由于人脸作为一个非刚体，其成像形变大，受到表情，姿态和光照变化等众多因素的影响，且对于样本的采集也受到时间，地点，环境，数量的限制。