Ear-parotic face angle: A unique feature for 3D ear recognition

• This is the first paper to investigate the ear-parotic face angle feature on 3D ear images.
• The ear-parotic face angle feature is defined and extracted from 3D ear images.
• The ear-parotic face angle feature is used for 3D ear indexing and recognition.
• Recognition speed and accuracy are improved by introducing the ear-parotic face angle feature.

This paper proposes a unique characteristic in 3D ear images: ear-parotic face angle of the person. The ear-parotic face angle feature is defined as the angle between the normal vector of the ear-plane and the normal vector of the parotic face-plane. It is a unique and stable feature in 3D ears, and is able to provide indexing identification as well as hierarchical verification solutions which enhance both the speed and accuracy of 3D ear recognition. The experimental results show that by using the angle indexing in identification, the search range is reduced to 9.69% from the original, which is a considerable reduction in time. The verification experiment also achieved an equal error rate (ERR) improvement (from 2.8% to 2.3%) by combing the angle feature with iterative closest point (ICP) method.