segmentation of certain regions defined on a firearm cartridge case for successful automatic matching of cartridge cases after a cartridge is fired , on the basis of the marks left on the cartridge cases fired . disclosed is a method for segmentation of a cartridge case base by using surface height matrix information comprising : detecting the center of the cartridge case base ; according to this center , obtaining the polar height matrix by subjecting the surface height matrix to polar transformation ; acquiring a one - dimensional signal , “ average height signal on the basis of radius ” , by calculation of the mean value on the radius axis applied on the polar height matrix ; determining regions similar to circle signal models on the ahsbr and detecting circles ; determining the firing pin mark region by threshold processing of the primer region surface height matrix . letters on the cartridge case base are detected by using slope matrices .