为了实现计算机对枪弹痕的自动比对,提出了一种采用三维形貌特征匹配的弹痕比对方法.首先通过改进的小波阈值函数对采集到的三维弹痕数据进行滤波以去除噪声干扰;去噪后,设计一维高斯滤波器按照弹痕的垂直方向提取有效信息取代采用经典二维高斯滤波器提取信息,能够减少弹痕信息的损失;最后经旋转、平移截取子弹次棱附近的有效弹痕信息,并计算不同子弹间对应次棱附近的弹痕纹理互相关测度,以判断痕迹所属弹头是否为同一型号枪支所发射.实验表明,所提方法能够提取弹痕的三维形貌特征,并能通过软件编程实现计算机对弹痕的自动比对,在现有数据范围内,其比对正确率不低于98%.
In order to achieve automatic comparison of bullet marks through computer technology,a method to match 3-D topography of different bullets was proposed.First,a proven threshold function of wavelet was used to de-noise the database of the collected 3-D bullet mark information.Second,as in accordance with the vertical direction of the bullet procedure,after de-noising the designed one-dimensional Gaussian filter was used to extract useful information to replace the classical two-dimensional Gaussian filter,and to reduce the loss of information.Finally,after the rotation and translation,we were able to retrieve useful bullet marks near the edge of each bullet,and calculate the cross-correlation measure between two different bullets to identify whether they were fired by the same type of firearm.Experiments show that the proposed method was capable of extracting 3D topography of bullets and realize the automatic comparison of bullet marks through programming.The accuracy rate of the identification was no less than 98% based on the current database.