identification of weapons

The Method of the Estimation of Uniqueness of Route Complexes in Secondary Traces

Introduction. The existing criteria for the pairing of traces on shot bullets can not be considered satisfactory. They turn out to be too strict, or do not take into account the identifiable information about the structure of the coincident traces. Therefore, today expert makes categorical conclusion about the identity of the compared traces mainly on bases on his own experience without assessing the probability of a random realization of this event. In this paper, a technique for estimation of the uniqueness of the route complexes in compared traces is considered. In general, the solution of this problem allows us to objectify the expert conclusions. Theoretical analysis. In work the model describing the structure of the routes displayed on the surface of a shot bullet is proposed. On the basis of this model, a method for assessment of the probability of a random coincidence of the routes (the uniqueness of the complexes of coinciding routes) is proposed. Priority list of the similarity of traces is proposed to be formed on the basis of an assessment of the uniqueness of complexes of coincident routes. Empirical analysis. The results of applying the proposed methodology using the proposed pairing criterion are presented. We used two models of weapons: AKM and Makarov pistol. Results. Comparison of test paired and unpaired traces with an assessment of the uniqueness of complexes of coincident routs showed the effectiveness of the proposed methodology and the objectivity of assessing the degree of similarity of the traces.

Method of the Binarization of Images of Traces on the Shot Bullets for the Automatic Assessment of Their Suitability to Identification of the Fierarms

Introduction. Nowadays, automatic identification of weapons on electronic databases involves the analysis thousands of images of similar tracks, including images which are not suitable for identification. It is necessary to exclude from the analysis traces not suitable for identification for reduction of volume of calculations and increase of their efficiency. The aim of this work is the analysis of methods for assessing the suitability of traces to the identification and develop image binarization techniquie, which ensures minimal distortion of the width tracks on traces on the shot bullets. Theoretical analysis. There are two methods for evaluating of the suitability of dynamic traces to identify the weapon. The first is to count the number of lines, the width of the tracks and the spaces between them. The second is to find the autocorrelation function (ACF). The ACF form is close to a delta function form for a trace suitable for identification. The second method is more promising for the analysis of traces on the shot bullets. Experimental part. The authors proposed an image binarizatiom technique based on the construction of the image brightness profile. Application of this technique to images of dynamic traces, which are oriented vertically, allows adequately display the main tracks on binary images. Conclusion. The proposed method allows to get a binary image of traces on the shot bullets suitable for automatic analysis of their suitability for identifying and further comparing traces.

The Concept of Mathematical Model of the Assessment of Uniqueness of Sets of Coinciding Routes in Secondary Traces on the Shot Bullets

Introduction. The model of an assessment of probability of casual combination of sets of routes in secondary traces is considered in article. Development of quantitative criteria of justification of a categorical positive conclusion about criminalistic identity of the compared traces, and also algorithm of formation in the automatic mode of the priority list is the purpose of the conducted research. Theoretical part. Twodimensional images of traces of rifling fields used for the simulation. The formulas for estimating the probability of an accidental match of trails were obtained. Experimental part. Calculations performed on the developed formulas, the dependence of the probability of an event compared to the number of trails should be shown. Conclusion. The theoretical possibility of estimating the probability of a random alignment sets of trails (the degree of matching features unique complexes) and its use in practice is shown in this paper.