3D capturing of fingerprints – on the way to a contactless certified sensor

Abstract

The purpose of this paper is to describe the development and performance tests of a contact-free fingerprint sensor, TrueFinger3D (TF3D). This contactless fingerprint sensor is designed to be perfectly interoperable with fingerprint image data captured with contact-based sensors or ink pads. This is achieved by acquiring a 3D dataset of the fingertip together with the image of the papillary lines. Based on the 3D data, the papillary lines image can be processed to compensate perspective foreshortening or even emulate deformation effects caused with contact-based sensors. The 3D measurement mechanism and the image processing are described in detail. The resulting fingerprint images taken by the contactless sensor are then matched with images taken by regular contact-based fingerprint readers at different force levels. The comparison shows that the geometric distortion of our contactless sensor TF3D is comparable to that of contact-based sensors deployed under regular conditions. Our test also shows that contact-based sensors operated under irregular or strong force conditions suffer from a substantial performance degradation, not seen with the contactless sensor TF3D, which has perfect reproducibility. The results also indicate perfect interoperability of the TF3D with any contact-based data and should therefore entitle the sensor to a certification for governmental use.