Advances in Fingerprint Technology.pdf

The next related set of requirements was the description of minutia
distribution using the same variables and accommodation of variations in
minutia density along with ridge pattern elements and singularities. Stoney
and Thornton effectively described the minutia distribution in the distal
portion of thumbprints, but they assumed a constant minutia density and
did not extend their study to include the pattern areas of fingerprints.
Requirements to incorporate two opposing orientations of minutiae and
three fundamental minutia types were met in the model.
Consideration of variation among prints from the same source — one
of the most critical requirements — was not seriously addressed by Stoney
and Thornton. Their tolerances for minutia position were derived from
successive printings under ideal conditions: these tolerances are far too low
to apply in actual fingerprint comparisons. Likewise, connective ambiguities
were not factored into Stoney’s ultimate 1.2% ceiling prediction.
Stoney and Thornton also did not meet their final requirement: providing
a means to determine the number of attempted comparisons in order to
assess the effect on the chance of false association. The significance of this
omission is questionable, given the criticisms of Robertson and Vignaux. 59
There are thus two fundamental limitations to the Stoney and Thornton
model. First, the survey, and therefore the model, were of very limited scope,
based exclusively on the distal (non-pattern) regions of pairs of thumbprints
from 206 males. Second, no mechanism was provided to accommodate prints
made under non-ideal printing conditions. Stoney and Thornton acknowledged
these weaknesses and their work remains the only model to have
attempted to describe minutiae within their ridge structure.
Similar to all the other fingerprint models proposed to date, the Stoney
and Thornton model remains untested. What is missing is the use of the
model to predict the frequency of occurrence of minutiae configurations,
followed by the testing of the accuracy of the prediction.
Champod and Margot Model (1995–1996)
Based on the work in Champod’s thesis, 11 Champod and Margot presented
a statistical model that utilized computer-generated frequencies of minutiae
occurrence and minutia densities. 60 Subsequently, this model was modified to
reclassify certain additional, closely spaced minutiae as combined minutiae. 61
Description of the Champod and Margot Model
Experimental Design
Champod and Margot designed a computer program to search for specific
minutiae on fingerprint images. One thousand inked fingerprints were