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

Iris scans use infrared light to capture the unique patterns of the iris inside the eye, not a standard digital video camera capturing external features.

Retinal scans use a low-intensity infrared light source to map the unique pattern of blood vessels at the back of the eye, requiring specialized equipment rather than a digital video camera.

Facial recognition uses a digital video camera to map and analyze external facial features such as the distance between eyes, nose shape, and jawline. Unlike other biometric methods, it works by processing a two-dimensional or three-dimensional image captured by a standard or specialized video camera. This makes it the correct match for the description of scanning external features through a digital video camera.

Signature kinetics (also called signature dynamics) measures behavioral characteristics such as pen pressure, speed, and rhythm during signing, not visual external features captured by a camera.