3D Whole Hand Targets: Evaluating Slap and Contactless Fingerprint Readers Sunpreet S. Arora1, Anil K. Jain1 and Nicholas G. Paulter Jr.2 1Michigan State University 2National Institute of Standards and Technology September 22, 2016 15th International Conference of the Biometrics Special Interest Group (BIOSIG), 2016

From Science Fiction to Reality

Increasing Availability of Fingerprint Readers Design and develop standard artifacts and procedures for consistent and reliable evaluation of fingerprint readers

Goal Design and fabricate whole hand 3D targets for evaluating multi-finger capture devices

Benefits Metrology agencies: repeatable evaluation of fingerprint readers Fingerprint vendors: improve imaging capability of fingerprint readers End users: understand and compare the advantages/limitations of different readers

Our Contributions Generate 3D whole hand targets by projecting 2D calibration patterns onto 3D hand surface Fabricate targets with material(s) similar in hardness and elasticity to human skin and optically compatible with various fingerprint readers Demonstrate utility of the targets for evaluating slap and contactless fingerprint readers

Generating 3D Whole Hand Targets

Partitioning 3D Hand Surface y z x Select finger region Separate finger region from rest 3D hand surface

Preprocessing 3D Finger Surfaces y z x Align the surface Make the surface dense Sample vertices and triangles Separate front and back 3D finger surface

Preprocessing 2D Calibration Patterns Extract Skeleton Smooth Dilate 2D calibration pattern

Mapping 2D Patterns to 3D Surfaces y z v x u Unwrap to 2D Map the 2D pattern Make the surface dense Frontal finger surface

Engraving 2D Patterns on 3D Surfaces y z x Displace the surface along the normals Compute the surface normals Frontal finger surface

Postprocessing 3D Finger Surfaces Combine front and back Stitch outer and inner surfaces Inner finger surface 3D finger surface

Stitch outer and inner surfaces Creating Glove Create inner surface Stitch outer and inner surfaces 3D hand surface

Electronic 3D Whole Hand Target

3D Printing Stratasys Objet Connex 350/500 (X & Y res: 600 dpi, Z res: 1600 dpi) Electronic 3D target 3D printed target parts Printing material similar in hardness and elasticity to human skin

Chemical Cleaning Manual cleaning 2M NaOH solution ( 3 hrs.) Cleaned target parts 3D printed target parts Rinse with water

Physical 3D Whole Hand Target Assembled 3D Whole Hand Target

Sample Slap Impression (1) Contact-based slap reader

Sample Slap Impression (2) Contactless slap reader

Sample Fingerprint Images Blue wavelength Red wavelength Blue + Red wavelength Images of the same target captured with single-finger optical readers using different wavelengths of light for fingerprint capture

Fidelity of 3D Target Generation Fidelity of features after 2D to 3D projection Similarity Score = 179; Threshold @0.01% FAR = 33

Fidelity of 3D Target Generation Fidelity of engraved features after fabrication Similarity Score = 473; Threshold @0.01% FAR = 33

Fidelity of 3D Target Generation End-to-end fidelity of features Similarity Score = 374; Threshold @0.01% FAR = 33

Intra-class Variability between 3D Target Impressions Similarity Score = 1494; Threshold @0.01% FAR = 33

Evaluating Contact-based Slap Readers Capture multiple slap impressions (5) and measure spacing in captured impressions Expected average ridge spacing: 8.62 pixels Observed average ridge spacing: 8.65 pixels

Evaluating Contactless Slap Reader Capture multiple slap impressions (5) and measure spacing in captured impressions Expected average ridge spacing: 8.27 pixels Observed average ridge spacing: 8.28 pixels

Conclusions and Future Work Design and fabrication of wearable 3D whole hand targets Fidelity assessment of the whole hand target synthesis and fabrication process Evaluation of slap and contactless fingerprint readers using whole hand targets Future Work Targets for capacitive readers Universal 3D targets for contact-based and contactless optical, and capacitive readers