Passive three-dimensional object authentication based on image sizing

Abstract

Techniques are described for passive three-dimensional (3D) object authentication based on image sizing, such as for biometric facial recognition. For example, during a registration routine, an imaging system captures images of a registering user's face at multiple distances. The images can be processed to extract registration dimensions, including individual deterministic structural dimensions, dimensional relationships that are static over changes in imaging distance, and dimensional relationships that changes predictably over changes in imaging distance. During an authentication routine, the imaging system again captures authentication images of an authenticating user's face (purportedly the previously registered user) at some authentication imaging distance and processes the images to extract authentication dimensions. Expected and actual dimensional quantities are computed from the authentication and registration dimensions and are compared to determine whether the authenticating user's face appears to be authorized as previously registered and/or is a spoof.