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Face recognition: New technologies, new challenges

Face recognition: New technologies, new challenges. Michael M. Bronstein. The coin that betrayed Louis XVI. ?. =. Modern challenges. Is this the same person?. What is a face?. =. +. PHOTOMETRIC (2D). GEOMETRIC (3D). What is more important: 2D or 3D?. =. +.

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Face recognition: New technologies, new challenges

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  1. Face recognition: New technologies, new challenges Michael M. Bronstein

  2. The coin that betrayed Louis XVI

  3. ? = Modern challenges Is this the same person?

  4. What is a face? = + PHOTOMETRIC (2D) GEOMETRIC (3D)

  5. What is more important: 2D or 3D? = +

  6. What is more important: 2D or 3D? = +

  7. Conclusion 1 • 3D data conceals valuable information about identity • Less sensitive to external factors (light, pose, makeup) • More difficult to forge

  8. The curse of expressions

  9. Is geometry sensitive to expressions? A A′ B′ B EUCLIDEAN DISTANCES: |A  B|  |A′ B′|

  10. Is geometry sensitive to expressions? A A′ B′ B GEODESIC DISTANCES: d(A,B)  d′(A′,B′)

  11. 1 0.8 0.6 0.4 0.2 0 -60 -40 -20 0 20 40 60 Conclusion 2 ERROR DISTRIBUTION • Extrinsic (Euclidean) geometry is sensitive to expressions • Intrinsic (Riemannian) geometry is insensitive to expressions • Expression-invariant face recognition using intrinsic geometry

  12. Mapmaker’s nightmare Find a planar map of the Earth which preserves the geodesic distances in the best way B B′ A′ A d(A,B) |A′  B′| PLANE (EUCLIDEAN) SPHERE (RIEMANNIAN)

  13. Isometric embedding A B A′ B′ EMBEDDING EUCLIDEAN RIEMANNIAN Expression-invariant representation of face = canonical form

  14. A remark from Gauss Theorema Egregium (Remarkable Theorem): A face has non-zero curvature, therefore, it is not isometric to the plane. Result: the embedding is only approximately isometric, and therefore, introduces an error. Carl Friedrich Gauss  (1777-1855)

  15. How to canonize a person? CANONIZATION CROPPING SMOOTHING 3D SURFACE ACQUISITION

  16. Examples of canonical forms

  17. Canonical forms ORIGINAL SURFACES CANONICAL FORMS Alex Michael

  18. Telling identical twins apart Alex Michael

  19. CAMERA PROJECTOR CARD READER MONITOR

  20. SCANNED FACE CANONICAL FORM DISTANCES

  21. Towards more accurate recognition • Embed one surface into another instead • of using a common embedding space • Avoid representation error • Beautiful theory: related to the • Gromov-Hausdorff metric

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