1. 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

2. From Science Fiction to Reality

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

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

5. 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

6. 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

7. Generating 3D Whole Hand Targets

8. Partitioning 3D Hand Surfacey z x
Select finger region
Separate finger region
from rest
3D hand surface

9. Preprocessing 3D Finger Surfacesy z x
Align the surface
Make the surface dense
Sample vertices and triangles
Separate front and back
3D finger surface

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

11. Mapping 2D Patterns to 3D Surfacesy z v x u
Unwrap to 2D
Map the 2D pattern
Make the surface dense
Frontal finger surface

12. Engraving 2D Patterns on 3D Surfacesy z x
Displace the surface along the normals
Compute the surface normals
Frontal finger surface

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

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

15. Electronic 3D Whole Hand Target

16. 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

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

18. Physical 3D Whole Hand Target
Assembled 3D Whole Hand Target

19. Sample Slap Impression (1)
Contact-based slap reader

20. Sample Slap Impression (2)
Contactless slap reader

21. 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

22. Fidelity of 3D Target Generation
Fidelity of features after 2D to 3D projection
Similarity Score = 179; FAR = 33

23. Fidelity of 3D Target Generation
Fidelity of engraved features after fabrication
Similarity Score = 473; FAR = 33

24. Fidelity of 3D Target Generation
End-to-end fidelity of features
Similarity Score = 374; FAR = 33

25. Intra-class Variability between 3D Target Impressions
Similarity Score = 1494; FAR = 33

26. 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

27. 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

28. 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