Some tubular cartridge has bigger plasticity.On cartridge production

because of extrusion

the case is not a regular circle ring.The cartridge case’s average inner and outer diameters are directly related to the ammunition’s performance

The current inner and outer diameter measuring technology can only measure single object to measure average diameters

it needs to get many images of the object to attain the average of the images. The method is proposed to attain cartridge images with area charge coupled device（CCD）camera

every image contains many objects.Two dimensional Fourier descriptor is used to recognize difference objects

according to cartridges being or not the same cartridge

to judge whether the cartridge is in the field.With the technology

many cartridges can be measured in the same time

extremely improved the measurement speed.The method adopts polynomial interpolation to realize sub-pixel edge detection.The precision is higher than 0.01 mm

reaches macron level.