Structured light: Lines of light are projected on a finger to illuminate the print. The light is warped by the ridges and valleys of the fingertip, allowing researchers to generate a 3-D fingerprint.
Shahram Orandi, team leader for the National Institute of Standards and Technology’s large-scale biometrics systems testing group, says 3-D fingerprinting is a hot area of development. Both the Department of Homeland Security and the National Institutes of Justice are interested in a non-contact system that can capture 3-D prints, ideally gathering data from multiple fingers at once. “There’s money out there and people are jumping at it,” Orandi says. Carnegie Mellon University and TBS Holdings are independently working on systems that use multiple cameras to capture the prints, for example. Both projects, as well as Kentucky’s, have received government grants.
“Almost everybody that tried to achieve 3-D capture has succeeded,” Orandi says. “The missing secret sauce is how to make these images compare to existing technology.”
Orandi describes the problem by equating a fingerprint to a tangerine peel. Trying to flatten out a carefully removed, large piece of peel will break the skin. The same thing happens with 3-D fingerprints, he says. Flattening them into 2-D images, so that they can be compared against the traditional prints in AFIS, results in cracks.
Wang says his system is able to flatten the 3-D representations it creates into two-dimensional prints without distorting the image. NIST is developing tools to test 3-D fingerprinting systems and assess the differences between some of the schemes being developed.
While he declined to go into detail on how Kentucky’s system fares against others, Orandi did say that it was among the top three he was familiar with.
The University of Kentucky researchers hope to improve their system, initially by speeding up the system so that the scanning and processing time is reduced to less than 0.1 seconds. The team also wants to be able to scan all 10 fingers at once, too. “Our goal is to have a box with multiple scanners in it … where you can just hold a relaxed hand pose” and capture the prints on all 10 fingers, says Lau.
When designing an embedded system choosing which tools to use often comes down to building a custom solution or buying off-the-shelf tools.