检材指纹与样本指纹变化的分析研究

Study on the Discrepancy of Fingerprints between the Questioned and the Known

目的依据数理统计所得出的数据分析检材指纹与样本指纹的变化规律;方法通过在检材指纹与其相对应的样本指纹上建立直角坐标系,得到各细节特征的坐标参数;再利用数理统计分析两者相对应的各细节特征变化的形成原因及规律;结果得出捺印时手指作用力方向的变化导致检材指纹与样本指纹细节特征之间产生距离差,手指的扭转变化使两者细节特征产生角度差;结论两者之间的变化是由于捺印时手指作用力方向不同、大小不同所导致。

Objective To analyze the discrepancy laws between the questioned and known fingerprints by statistical data. Method The questioned and known fingerprints were put in Cartesian coordinates, where the coordinate parameters of every detailed characteristic of fingerprints were obtained. Then the discrepancies between every corresponding detailed characteristic of the two samples were analyzed with statistics to find out the causes and laws of those discrepancies. Results When pressing a fingerprint, the changes of force direction on the finger will lead to the distance discrepancies, and the changes of twisting and turning will lead to the angle discrepancies. Conclusion The discrepancies between the questioned and known fingerprints are caused by the different force directions and strengths when pressing. This study will provide a new method for the identification of deformed fingerprints.