Once the right biometric technology is selected, the next step is to decide on the approach that will actually make it work within the application. Typically there are two types of applications; either a large system exists or is being purchased, or there is no existing access control system in place. The size of an access control system generally is defined by the number of doors it controls.
Normally, when a biometric characteristic such as hand geometry or a fingerprint is enrolled, the information is stored in an enrollment template within the biometric system. It then becomes the credential against which future access attempts are compared. Depending on the type of biometric, the size of the template may range from as low as nine bytes up to 512 bytes or more. Most access control systems now in existence do not have a data field for storing biometric templates, although some systems now are becoming available with the ability to manage this information. Over the next few years, most access control manufacturers probably will move in this direction until biometric devices are eventually integrated as much as any other device.