Hand geometry recognition is
|“||a biometric modality that uses the physical structure of an individual's hand [ hand geometry ] for recognition purposes.||”|
Hand geometry recognition systems have been in use for almost thirty years for access control to facilities ranging from nuclear power plants to day care centers. Hand geometry systems use an optical camera and light-emitting diodes with mirrors and reflectors to capture two orthogonal, two-dimensional images of the back and sides of the hand. Ninety-six measurements are then extracted and a 9 byte template is derived, making it the smallest in the biometric industry.
How it works Edit
Hand geometry recognition technology measures the width, height, and length of the fingers, distances between joints, and shapes of the knuckles. The oldest hand geometry technique was based on the length of fingers and the thickness and curvature of the webbing between them. Other techniques use the size and proportions of the hand or the distances between the joints of the fingers, infrared hand topography, palm print and crease geometry, or transverse hand geometry (viewing the sides of the fingers to measure hand thickness as well as shape). Some of these techniques combine the biometric measurement with a personal identification number.
Although the basic shape of an individual’s hand remains relatively stable over his or her lifetime, natural and environmental factors can cause slight changes. The biggest measurement problems with these devices involve people who wear rings on their fingers or whose fingers are stubbed or swollen.
In use, an individual enters a personal identification number (PIN) code to claim an identity and then places his or her hand on a device that takes a picture of his hand. Later, when the user needs to be identified he places his hand on a device that compares the characteristics of his hand with the stored image.
One of the shortcomings of the hand geometry biometric characteristic is that it is not highly unique — thus limiting the value of a hand geometry system to verification tasks only. Consequently, hand geometry is not suitable if there is a need to search the biometrics database to determine if a person has previously enrolled in the database or is in a watch list. However, hand geometry is viable for verifying claimed identity when another biometric technology is used for the identification check during enrollment.
A privacy protection analysis should refer to the process used to select the hand geometry modality to inform the participants (the individual and the organization) of the actual capabilities and limitations of the biometric technology and the correlating level of reliance that should be placed on the resulting matches made by the system.
- ↑ Biometrics Identity Management Agency, Biometrics Glossary, at 33 (Ver. 5) (Oct. 2010) (full-text).