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Automated comparison of striation marks with the system GE/2



Michael Heizmann


Investigative Image Processing II, Z.J. Geradts, L.I. Rudin (eds.), Processings of SPIE, Vol. 4709, 2002.



In this paper, the newly developed system GE/2 for the automated identification of toolmarks and firearms is presented. It is based on a signal processing strategy that enables an automated evaluation of pictures taken from striation patterns. To this end, a signal model is introduced which is suitable to describe the characteristics of groove textures. This signal model can be adapted to both forensically important groove types: straight grooves, which can be found on pristine bullets, and curved grooves, which are typical for toolmarks and deformed bullets.
To obtain high quality data, a powerful imaging approach is presented. The underlying strategy, which is based on fusion techniques, is applicable to both illumination problems and focussing issues. To ensure a high reliability in the automated comparison, characteristic features, which are called "signatures," are required. To this end, a newly developed strategy is proposed to straighten curved grooves by means of the signal model mentioned above. Based on the signatures obtained, an automated comparison on the basis of correlation techniques is applied. As a result, the marks in question are sorted in a descending order with respect to the detected similarity. Here, a benchmarking test for comparison algorithms is introduced which makes it possible to compare the efficiency of different systems.
Finally, the realized system GE/2 is presented, consisting of the Image Acquisition Station and a computer to perform the processing of the data. The benchmarking test is applied to the system GE/2, which proves its high qualification for forensic applications.