Popular Biometric Methodologies — What
are they?
You will see reference to a number of biometrics, some
of which are rather impractical even if technically
interesting. The ‘popular’ biometrics seem
to gravitate at present around the following methodologies.
Fingerprint verification.
 There
are a variety of approaches to fingerprint verification.
Some of them try to emulate the traditional police
method of matching minutiae, others are straight pattern
matching devices, and some adopt a unique approach
all of their own, including moiré fringe patterns
and ultrasonics. Some of them can detect when a live
finger is presented, some cannot. There is a greater
variety of fingerprint devices available than any other
biometric at present.
Potentially capable of good accuracy (low instances of false acceptance) fingerprint
devices can also suffer from usage errors among insufficiently disciplined users
(higher instances of false rejection) such as might be the case with large user
bases. One must also consider the transducer / user interface and how this would
be affected by large scale usage in a variety of environments. Fingerprint verification
may be a good choice for in house systems where adequate explanation and training
can be provided to users and where the system is operated within a controlled
environment. It is not surprising that the workstation access application area
seems to be based almost exclusively around fingerprints, due to the relatively
low cost, small size (easily integrated into keyboards) and ease of integration.
Hand geometry.
 As
the name suggests, hand geometry is concerned with
measuring the physical characteristics of the users
hand and fingers, from a three dimensional perspective
in the case of the leading product. One of the most
established methodologies, hand geometry offers a good
balance of performance characteristics and is relatively
easy to use. This methodology may be suitable where
we have larger user bases or users who may access the
system infrequently and may therefore be less disciplined
in their approach to the system. Accuracy can be very
high if desired, whilst flexible performance tuning
and configuration can accommodate a wide range of applications.
Hand geometry readers are deployed in a wide range
of scenarios, including time and attendance recording
where they have proved extremely popular. Ease of integration
into other systems and processes, coupled to ease of
use makes hand geometry an obvious first step for many
biometric projects.
Voice verification.
 A
potentially interesting technique bearing in mind how
much voice communication takes place with regard to
everyday business transactions. Some designs have concentrated
on wall mounted readers whilst others have sought to
integrate voice verification into conventional telephone
handsets. Whilst there have been a number of voice
verification products introduced to the market, many
of them have suffered in practice due to the variability
of both transducers and local acoustics. In addition,
the enrolment procedure has often been more complicated
than with other biometrics leading to the perception
of voice verification as unfriendly in some quarters.
However, much work has been and continues to be undertaken
in this context and it will be interesting to monitor
progress accordingly.
Retinal scanning.
 An
established technology where the unique patterns of the retina are scanned by
a low intensity light source via an optical coupler. Retinal scanning has proved
to be quite accurate in use but does require the user to look into a receptacle
and focus on a given point. This is not particularly convenient if you are a
spectacle wearer or have concerns about intimate contact with the reading device.
For these reasons retinal scanning has a few user acceptance problems although
the technology itself can work well. The leading product underwent a redesign
in the mid nineties, providing enhanced connectivity and an improved user interface,
however this is still a relatively marginal biometric technology.
Iris scanning.
 Iris
scanning is undoubtedly the less intrusive of the eye
related biometrics. It utilises a fairly conventional
ccd camera element and requires no intimate contact
between user and reader. In addition it has the potential
for higher than average template matching performance.
As a technology it has attracted the attention of various
third party integrators and one would expect to see
additional products launched in due course as a result.
It has been demonstrated to work with spectacles in
place and with a variety of ethnic groups and is one
of the few devices which can work well in identification
mode. Ease of use and system integration have not traditionally
been strong points with the iris scanning devices,
but we can expect to see improvements in these areas
as new products are introduced.
Signature verification.
 Signature
verification enjoys a synergy with existing processes that other biometrics do
not. People are used to signatures as a means of transaction related identity
verification and would mostly see nothing unusual in extending this to encompass
biometrics. Signature verification devices have proved to be reasonably accurate
in operation and obviously lend themselves to applications where the signature
is an accepted identifier. Curiously, there have been relatively few significant
applications to date in comparison with other biometric methodologies. If your
application fits, it is a technology worth considering, although signature verification
vendors have tended to have a somewhat chequered history.
Facial recognition.
 A
technique which has attracted considerable interest and whose capabilities have
often been misunderstood. Extravagant claims have sometimes been made for facial
recognition devices which have been difficult if not impossible to substantiate
in practice. It is one thing to match two static images (all that some systems
actually do - not in fact biometrics at all), it is quite another to unobtrusively
detect and verify the identity of an individual within a group (as some systems
claim). It is easy to understand the attractiveness of facial recognition from
the user perspective, but one needs to be realistic in ones expectations of the
technology. To date, facial recognition systems have had limited success in practical
applications. However, progress continues to be made in this area and it will
be interesting to see how future implementations perform. If technical obstacles
can be overcome, we may eventually see facial recognition become a primary biometric
methodology.
There are other biometric methodologies including the use of scent, ear lobes
and various other parameters. Whilst these may be technically interesting, they
are not considered at this stage to be workable solutions in everyday applications.
Those listed above represent the majority interest and would be a good starting
place for you to consider within your biometric project. The sections of this
paper dealing with performance issues and user psychology offer a further insight
into the application of these devices.
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