3D Targets for Evaluating Fingerprint Readers

Standard calibration targets are typically used for calibrating the imaging pathway of fingerprint readers. However, there is no standard method for evaluating fingerprint readers in the operational setting where variations in finger placement by the user are encountered. The goal of this research is to design 3D targets for repeatable operational evaluation of fingerprint readers. 2D calibration patterns with known characteristics (e.g. sinusoidal gratings of pre-specified orientation and frequency, synthetic fingerprints with known singular points and minutiae) are projected onto a generic 3D finger surface to create electronic 3D targets. A state-of-the-art 3D printer (Stratasys Objet350 Connex) is used to fabricate the 3D targets with material similar in hardness and elasticity to the human finger skin. Our experimental results show that the (i) fabricated 3D targets can be imaged using three different (500/1000 ppi) commercial optical fingerprint readers, (ii) salient features in the 2D calibration patterns are preserved during the synthesis and fabrication of 3D targets, and (iii) intra-class variability between multiple impressions of the 3D targets captured using the optical fingerprint readers does not degrade the recognition accuracy. We also conduct experiments to demonstrate that the fabricated 3D targets can be used for operational evaluation of fingerprint readers. Keywords—3D targets, fingerprint reader evaluation, 2D calibration patterns, 3D printing, 2D pattern to 3D surface projection.