accurate contactless 3D fingerprint identification system
The research team of The Hong Kong Polytechnic University
(PolyU) has developed a system for three-dimensional (3D) fingerprint
identification by adopting ground breaking 3D fingerprint minutiae recovery and
matching technology, pushing contactless biometric technology into a new realm
of speed and accuracy for use in identification, crime investigation,
immigration control, security of access and forensic applications at an
affordable cost.
Automated contact-based 2D fingerprinting identification is
commonly used by law enforcement agencies to identify people. However,
contact-based acquisition of biometric scans by rolling or pressing fingers
against a hard surface such as glass, silicon or polymer often results in
partial or degraded images due to skin deformations, slippages or smearing.
This produces images that are not fully useful for the identification.
Non-contact fingerprint systems, on the other hand, avoid direct contact
between the imaging sensor and the elastic surface of the skin, and can thus
reduce inaccuracies due to problems associated with contact-based systems.
Although there are emerging contactless 3D systems, they tend
to be very expensive and bulky due to their use of multiple cameras or
structured lighting systems.
The research team led by Dr Ajay Kumar, Associate Professor
of Department of Computing overcomes the limitations of contact-based 2D
biometric scans and maximises the advantages from the contactless 3D systems.
The minutiae features from the fingerprint ridges – such as
ridge ending and bifurcation are universally considered to be the most reliable
of fingerprint details, ensuring that each fingerprint is unique. About
40-45 minutiae points can be recovered from a fingerprint on an average.
The more minutiae points are matched, higher is the confidence and
reliability in the matching.
All fingerprinting systems commercially available today still
recover the minutiae details in 2D form, i.e. by locating the minutiae position
and minutiae orientation in 2D spaces. In Dr Kumar’s research, 3D
fingerprints are represented by minutiae height and minutiae orientation (i.e.
gradient of minutiae ridges) in 3D spaces on top of the representations in 2D
spaces named above. This means our 3D system can more uniquely represent
fingerprints with the extra information given by describing two more
measurements.
To achieve 3D fingerprint minutiae recovery and matching,
firstly the team has shifted away from the standard use of multiple cameras in
3D fingerprint identification system to the innovative use of a single,
low-cost digital camera coupled with a few LED light sources controlled by a
computer. This allows researchers to efficiently acquire high-frequency
information in 3D fingerprints using advanced proprietary 3D fingerprint
template generation algorithms to recover 3D minutiae features. With such
3D minutiae details recovered, for the first time in the world, PolyU research
team has been able to accurately and reliably match 3D fingerprints using its
matching algorithms.
The compact size, high accuracy of around 97%, reduced cost
of up to $780, the faster processing time of approximately 2 seconds, and
reduced amount of equipment needed render the system better than the currently
used commercial 3D counterparts. The contactless system is also more
hygienic than contact-based 2D systems, an added advantage in a world
increasingly concerned about the inadvertent spread of disease. Given its
ultimate practicality, the system is ripe for commercialization with several US
patents granted on its ground breaking technologies.
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