performs the morphological operations and dilation to "shave" observations off of the interior or exterior of a cartridge case surface matrix.
preProcess_erode(x3p, region, morphRadius = 50)
an x3p object
either "interior," meaning the observations around the firing pin hole will be eroded, or "exterior," meaning the observations around the outer edge of the cartridge case primer will be eroded
controls the amount of erosion. Larger values correspond to a larger (circular) morphological mask leading to more erosion.