The Study On The Analysis And Application Of Level3Features In Fingerprint Identification Of Civil Cases

The tradition using fingerprint as a form of recognition of a contract has lasted along history in China. And even today we often use fingerprint identification to dealwith problems in civil cases. However fingerprints in many contracts have insufficientminutiae to make an accurate conclusion in fingerprint identification, just becausethey are always presented as fragmentary or vague or distorted ones. As this situationprevails in most contracts, we are promoted urgently to exploit more feasible featuresto act as the basis of the identification, and such perspiration counts a lot. In thisarticle, the author try to study the condition, possibility and method about using level3in fingerprinting involved in civil litigations.This article can be divided into four parts as follows:The first part of this article has introduced the history and conception oflevel-3,and make an analysis of the conception of level3at the same time. In additionthis part put forward the value of studying level3. The exploration of using level3features sprouted in the time of Locard, but level3features truly became being valuedin the fingerprint identification philosophy in1970s,thus being used and popular inpractice gradually. The nomenclature level3derives from the hierarchicalclassification system, and defines the small shapes in friction ridges in the dimensionof the ridge. Level3features are smaller than level1and level2, and mainlyconclude pores, ridge contours, the alignment of ridge unit, scars, creases, etc. All ofthese features are unique and persistent, thus could be the unique biometric features toindividualize.The second part is dominated by two experiments. The basic problem in usinglevel3is about the degree of reflection in level3features and how to extract themaccurately. So before discuss how to use level3features, the author first conducts two correlative experiment to explore the conditions relate to reflecting level3featuresand how to get the available image to satisfy the requirement of extract level3. Thispart first analyzes the basic conditions on achieving exemplars such as pressure andbearing objects through the experiment of one particular finger, thus explores the bestconditions. As to the conditions of reflection in level3, the element experiment showsthat:(1)the pressure surrounding3N which ranges from1N to5N could best reflectmost kinds of level3features at the same time;(2)a good reflection of level3need aproper moisture of the friction skin but not means to preserve water in it;(3)the softdegree of cushioning material raging in a small normal scope does not exert aninfluence apparently;(4)photo paper and black ink are the best material group amongall the pigments and papers used in the experiment. Then the second experimentpoints to more than one person and bases on the element experiment. It tries to testand verify the best conditions which were concluded from the element experiment.Moreover, this experiment will also analyze the individual differences in theexperiment; and it will summarize realistic conditions on making fingerprints, studystability and reflection of level3in different conditions. The further confirmatoryexperiment demonstrates that:(1) press down one’s fingerprint using combination ofmaterials black ink and photo paper can gain a good effect;(2)conforming to the normof making fingerprint and keeping the pressure in a single direction contributes to agood reflection of level3;(3)other pigments in the experiment perform worse thanblack ink in the reflection of level3when making a fingerprint;(4)the effect ofreflection is subjected to the difference between sex and individual;(5)the statisticsfrom the simulation of making fingerprints when sign contracts shows that thepressure exerted by most subjects in the experiment conforms to tolerance range forthe reflection in level3.The third part states how to use level3features in the fingerprint identificationof civil cases on the basis of the element experiment and foreign experience. It statedthe selection of equipment for images, and also has summarized the method andstandard of achieving exemplars. As to achieving exemplars for level3features, theexperiments show we can use photo paper and black ink as materials, the idealpressure depend on the situation of the test fingerprints and the individual uniquenessin friction skin. Other respects on gaining fingerprint exemplars should be just accordto the norm strictly. As to specific method of comparison, we should largely absorbthe experience of predecessors’, and exert cautious analysis. The forth part has made a further analysis on the values and limitations ofapplying level3features. Level3features can also play a role in supplying clues incomparison and recognizing fake fingerprints in the process fingerprint identification,besides act as the basis of individualization. The limitations of using level3featuresappears as non-universality, the uncertainty and instability in reflection and lesspersistent than level1and level2features.