Dear rob_in_nm-ga;
Thank you for allowing me an opportunity to answer your interesting
question.
I have spent more than two decades in law enforcement and in my
current capacity as an evidence technician I conduct forensic studies
and do business with a state crime laboratory on a daily basis. As
such, I have been examining, submitting and classifying fingerprints
for years. I can tell you straight away that there are no typical
dimensions for fingerprints related to race, gender, age or any other
fixed descriptor of a human being. There is no method by which a
technician can examine a fingerprint and say with absolute certainty
(or even measurable probability) that a person who made the print was,
for example, an Asian male, any more reliably than he could say that
the person who made the print was a blonde male or tall woman. While
there are some obvious physiological characteristics common in the
skin of some human races, there are also significant physiological
differences between people of the same races according to the region
in which they might live, the work that they do, their age and their
life-style. Among these, there are so many other factors that affect
the physiological characteristics of individuals as to make the
probability of recurrence among a specific group sharing common traits
immeasurable. A single individual’s probability of inheriting certain
genes alone that would make the underlying ridges of skin behave in a
predictable manner would be incalculable in itself, as an infinite
number of probabilities exist.
Our fingerprint patterns are determined at birth. The pattern you have
is random, and only directly related to the contour of the subdural
tissues beneath the individual’s skin. These patterns appear not just
on our fingertips, but also over the entire surface of our bodies.
They are most prominent on our hand and feet, but they can also be
seen elsewhere. You can imagine then, that the surface skin on the
elbow of an Asian male, when imprinted, is really no different in
appearance from the surface skin on the elbow of a Caucasian female.
The same is true for identical twins, which consistently have notably
different fingerprint patterns. If we had eight sets of fingerprints,
each belonging to one person in a group consisting of three sets of
twins, two unrelated males of any race and two unrelated females of
any race, there would be absolutely no way to visibly tell who was
related to whom or what race or gender any of the examples belonged to
based on any of the features you mentioned.
There are however a few common features that all fingerprints share
with one another. These are called “class characteristic” Among these
characteristic patterns are loops, arches, whorls and accidentals, but
there are many others. About 60% of all fingerprints, regardless of
race or other factors, are classified as “loops”. Other
characteristics include “crosses” and “lakes”. “Crosses” are the
ridges that seem to cross over one another at various points and
“lakes” are the voids that exist between the ridges, particularly in
areas where multiple crosses leave what appears to be a relatively
smooth surface in the middle. A person’s fingerprint can be digitized
(in the old days this was done by hand using a magnifying glass and a
piece of paper) and the physical attributes (patterns, intersecting
points, etc) are each assigned values, which are then fed into a
computer database. The most widely used database is known as AFIS
(Automated Fingerprint Identification System) but some areas use a
system called FACTS (Fingerprint Analysis and Criminal Tracing
System), which can interface AFIS and also operates on the same
principle. If the fingerprint is ever scanned in the future, the
computer can check that print against the standard value system used,
and identify that print as being unique among millions of others.
I hope you find that that my research exceeds your expectations. If
you have any questions about my research please post a clarification
request prior to rating the answer. I welcome your rating and your
final comments and I look forward to working with you again in the
near future. Thank you for bringing your question to us.
Best regards;
Tutuzdad-ga
INFORMATION SOURCES
FINGERPRINT SECURITY
http://nv.essortment.com/fingerprintssec_rwkx.htm
FINGERPRINT ANALYSIS AND CRIMINAL TRACING SYSTEM (FACTS)
http://www.cmcltd.com/facts/FACTS.htm
AFIS
http://onin.com/fp/afis/afis.html
SEARCH STRATEGY
SEARCH ENGINE USED:
Google ://www.google.com
SEARCH TERMS USED:
FINGERPRINTS FACTS
AFIS
FORENSIC FINGERPRINTS
COMMON FINGERPRINT CHARACTERISTICS
PHYSIOLOGICAL DIFFERENCE FINGERPRINT CHARACTERISTICS |
Request for Answer Clarification by
rob_in_nm-ga
on
13 Jun 2003 13:23 PDT
Dear tutuzdad --
Thank you for your reply. While your information is very good and
quite thorough, it's perhaps a bit different than I was intending.
I am the CTO of a biometrics company (not fingerprint) and wish to do
some optical modeling of the imaging characteristics of optical
fingerprint reader. In order to do so, I need the actual dimensions of
the ridges that make up the arches, loops and whorls. I can look at my
own finger as well as others to see that the ridges are maybe 0.8mm
center-center and perhaps go as deep as 0.2-0.3 mm, but I was hoping
to get a more informed estimate of the mean values and popolation
ranges for these dimensions.
I sure would appreciate it if you could supply this information.
Thanks.
Regards.
|
Clarification of Answer by
tutuzdad-ga
on
13 Jun 2003 14:40 PDT
Dear rob_in_nm-ga;
As you perhaps already know, one of the key peices of data many
fingerprint readers use to validate the identity of the user is the
depth of the fingerprint valleys and height of the fingerprint ridges
of the print being scanned. Logically then, it is appparent that this
characteristic varies from one person to another. Because of the
consistent nature of these differences and the wide variety of
potential measurements, nothing about a fingerprint measurement is
typical...not among races, genders or any other similarly defined
groups of human beings. It goes without saying that a fingerprint
ridge normally isn't 1cm deep, but because a reader's measurements are
so precise and so miniscule, it could use this type data to
distinguish between a person who's fingerprint reading indicated a
valley depth of 0.234mm from one who's fingerprint measured 0.235mm.
To add to the complexity of the issue is the fact that a fingerprint
ridge is not round. Through a misroscope, you can clearly see that it
is quite rough and craggy, much like the countour of a mountain peak
(but eroding, growing and changing much more often in a living human
being, of course). Each epidernal ridge in our integument system, and
each segement of each ridge in the system varies in height and depth.
The single fingerprint of one person might have thousands of different
measurements. Each finger then represents tens of thousands of varied
depth measurements - each hand, each person, and so on so as to make
such an estimate about all persons (or even a single person for that
matter) impossible to make. Furthermore, skin changes with age, with
the seasons, with activity, etc, making it impossible to survey the
average depth of the valleys and height of the ridges of even one
individual's fingerprints with any degree of accuracy, much less an
entire population.
Take a look at this photo of a ridge as seen through a miscroscope
(from a side view) and see just how inconsistently and randomly
contoured a ridge can be in only one person, in only one microspopic
area of space: http://lifesci.rutgers.edu/~babiarz/histo/skin/thck2.htm
Unfortunately, I cannot give you what does not exist. The fact
remains, in response to your question as stated above, that there are
no "typical" measurements (maximums or minimums) with regard to
fingerprint size, features, or attributes and there is no known
correlation between any common fingerprint patterns and other defining
characteristics in humans.
Regards;
tutuzdad-ga
|
Request for Answer Clarification by
rob_in_nm-ga
on
14 Jun 2003 09:42 PDT
Dear Tutuzdad,
I understand the variability of these parameters across people.
However, like many other aspects of human factors, this variability
can, without question, be quantified. The only question is has this
quantification been done and has it been published in a way accessable
to the Google researchers. I suspect the answer is yes, and clinical
researchers such as the one who generated the photo in your link have
probably done this type of study.
In summary, I am looking for dimensions that quantify the size of the
ridges (depth and spacing) of fingerprints across the human
population, as well as the extremes at say the 95th percentile.
For further clarity, I am definitely ***not*** looking for information
on the macro-structure of fingerprints or attempting to associate
particular fingerprint features with particular demographic groups.
If you can dive back in and generate these numbers that would be
great. Otherwise, please release the question so that another
researcher might have a chance.
As always, please don't hesitate to contact me if you have further
comments or questions.
Regards,
rob_in_nm
|
Clarification of Answer by
tutuzdad-ga
on
14 Jun 2003 13:47 PDT
Dear rob_in_nm-ga;
Ah, I apologize for the misunderstanding on my part. I see what you
are saying now. Your research requirements aren’t related to “unique”
qualities of fingerprints at all. Ok, let’s try and uncover some
anatomical and topographical data, shall we?
Continuing my research, I found this statement from Peter C. Burridge,
who is Director/Principal of the company Fingerprint & Forensic
Services Limited, an Auckland-based firm with 10 years in the
business. He has been a career Police Officer, having served with both
the British South Africa Police (Rhodesia) and the New Zealand Police,
for over 36 years, retiring as Principal Fingerprint Officer and O/c
Fingerprint Section, Auckland, in 1999:
"One of the basic principals of impression identification is that the
papillary ridges are so highly variable that their characteristics,
even in a small area of a finger, palm or sole of foot, are not
duplicated again in another region or in a different individual.
Further, that the ridges are unchanging and permanent (unless major
damage occurs to the lower level of skin). It's interesting that the
average ridge breadth of a male is 0.48mm and a female 0.43mm."
Unfortunately, he does not appear to confirm the accuracy of this
statement on his site by way of a referenced or verifiable study,
however.
QUESTION OF FINGERPRINTS
http://www.ecoliving.co.nz/nzsecurity/mag/June-July2002/A%20QUESTION%20OF%20FINGERPRINTS.htm
---------------------------------------------------------------
In REALISM WHITE PAPER, by MIT, the Laboratory for Human and Machine
Haptics staff published this statement regarding their biomechanics
experiments. IN the course of the study it became necessary to create
and artificial skin in order to measure the pressure at the skin to
surface interface with fine spatial resolution:
"Over the last year, we have begun measuring the pressure distribution
at the skin/object interface with sub-millimeter spatial resolution.
Pressure distributions developed by cylinders ranging from 1/8 to
1-inch radius are being measured, using a 16 x 16 array of capacitive
pressure sensors. A motion platform indents the cylinder with good
(~12 micron) precision, while a load cell measures net reaction force.
To achieve spatial resolution finer than the spacing of the sensor
elements (2mm on center), we are using deconvolution. By taking 500
measurements, each shifted slightly via the motion platform, we are
obtaining fine spatial resolution (1 sample/0.1mm). The system is now
being calibrated on data from a series of micro-machined ridges
separated by 2.0 to 0.020 mm."
We can assume by this statement that 2.0mm would be the maximum depth
of papillary ridges for the purposes of their study and 0.020mm is, at
the lowest end of the spectrum, the minimum depth.
Here they speak about the actual finger pag skin itself:
"Images of fingerpad skin of six human subjects showed three distinct
layers up to a depth of about 1.2mm. Comparison images of fingertip
skin on the dorsal side also showed a layered structure, with lesser
thickness for the first two layers. The data obtained is consistent
with known anatomical information that the three layers imaged are the
stratum corneum, the rest of the epidermis, and the top region of the
dermis."
REALISM WHITE PAPER
http://rleweb.mit.edu/Publications/pr144/32.htm
--------------------------------------------------------
RIDGES AND FURROWS makes this statement in its estimation if how many
ridges are in a given area (as a generalization):
"The skin over most of the body is relatively smooth. 'Friction
Ridges', however, are found on the digits, palms and soles. They are
called 'friction' ridges because of their biological function to
assist in our ability to grasp and hold onto objects. They have been
compared to fine lines found in corduroy, however unlike corduroy,
ridges vary in length and width, branch off, end suddenly and, for
the most part, flow in concert with each other to form distinct
patterns. The ridge path can sometimes be quite fragmented...so much
so as to show what appears to be individual ridge "units" present on
the volar surface. There are approximately 2,700 ridge "units" per
square inch of friction skin. Each ridge "unit" corresponds to one
primary epidermal ridge (glandular fold) formed directly beneath each
pore opening."
RIDGES AND FURROWS
http://www.ridgesandfurrows.homestead.com/friction_skin.html
----------------------------------------------------------
Interestingly, I found this comment by social psychologist David
Myers:
"Most people have more fingerprint ridges on their right hand than on
their left"
DAVID G MYERS, SEXUAL ORIENTATION
http://www.davidmyers.org/sexorient/textbksumm7e.html
This statement refers to a study done by Canadian researchers seen
here:
DERM: FINGERPRINTS AND HOMOSEXUALITY
http://www.handanalysis.net/library/derm_gay.htm
-------------------------------------------------------------
Based on what very little there is on this topic, gleaning portions
from the information shown above, the conclusion appears to be this:
The average ridge breadth of a male is 0.48mm and a female 0.43mm.
On average, ridges are separated by 2.0 to 0.020 mm.
There are approximately 2,700 ridge "units" per square inch of
friction skin.
On average, the finger pad skin of a human has three distinct layers
up to a depth of about 1.2mm.
Certain lifestyles, orientations and other deciding factor can have an
impact on what is known to be the norm with regard to ridges of the
friction skin.
I’m sorry it took me a while to get on the same school of thought as
you. Once I realized that the information you were trying to get was
really unrelated to the uniqueness of fingerpints (as in the legal
point of view), I approached your question from an anatomical point of
view and was able to round up what I believe is the information you
require. If this is more in tune with the information you are needing
I’d welcome your final rating.
Regards;
Tutuzdad-ga
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