For citation:
Fedorenko V. A., Sorokina K. O. Compensation of Distortions on Digital Images of Traces of the Weapon on the Shot Bullets Caused by Curvature of the Studied Surface. Journal Izvestiya of Saratov University. Economics. Management. Law, 2017, vol. 17, iss. 1, pp. 91-95. DOI: 10.18500/1994-2540-2017-17-1-91-95
Compensation of Distortions on Digital Images of Traces of the Weapon on the Shot Bullets Caused by Curvature of the Studied Surface
Introduction. The purpose of work is: an assessment of distortions of images of traces on the shot bullets caused by curvature of the studied surface; working off of a technique of compensation of distortions. Theoretical analysis. Nodal point method was selected for the evaluation of image distortion and compensation. The method is based on the principle that each nodal point in the distorted image must comply with clearly known one anchor point to the undistorted image. In this case, the coordinates of pixels in the distorted image can be converted into coordinates that will conform these pixels on the undeformed image. Model experiment. The secondary trace should be modeled in 1:50 scale for evaluating the distortion. Model of trace was photographed one frame (similar to shooting on the microscope) and by 4 frames (similar to scanning through an automated ballistic identification system (ABIS)). The difference image distortion was determined by superimposing images. Experimental studies. Studies have been carried out for bullets, the shot from a Makarov pistol caliber 9 mm. The compared trace has been photographed by means of a comparative microscope, and also scanned on ABIS “POISC”. The resulting images have been provided to one scale and resolution. Comparison of the original image showed that paired attributes are located near the periphery, do not coincide due to the significant distortion of the image, obtained in the microscope. Matching tracks are aligned in the center and at the periphery of images after the conversion of the distorted image. Conclusions. Digital images of secondary traces from an optical microscope can be used in an digital database on bullets of the automated ballistic system after compensation of distortions by method of nodal points
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