Which type of scan measures a person's external features through a digital video camera?

Iris scans analyze the unique colored ring surrounding the pupil of the eye using near-infrared light, not a standard digital video camera capturing external features.

Retinal scans use a low-energy infrared beam to map the unique blood vessel patterns on the back of the eye, which is an internal feature not visible to a video camera.

Facial recognition systems use digital video cameras to capture images or video of a person's external facial geometry, analyzing features such as the distance between eyes, nose shape, and jaw line to match against stored biometric profiles. This is the only biometric method listed that relies on an external digital video camera and visible physical features.

Signature kinetics (dynamic signature recognition) analyzes behavioral characteristics such as pen pressure, speed, and stroke order during signing, not physical features captured by a video camera.