FIGURE 2. Multibiometric identification.

Sources of information in a multibiometric system include (clockwise from the top) using different sensors to capture the same biometric trait; using more than one independent trait; taking more than one sample of the same trait (for example, the same fingerprint or iris scan); taking multiple instances of a trait (prints of both the left and right index finger, or the irises of right and left eyes); and more than one type of representation of the same trait. The US-VISIT immigration scheme is a multibiometric system based on multiple instances (two fingerprints) with the future potential also to take a multiple-trait approach, fusing fingerprint data with face-recognition technology.