Estimation of pith position in untreated log ends in sawmill environments

Two related methods for automatic estimation of the pith position, i.e., the centre of the annual rings, in wood log end face images are presented. We use images that depict untreated log end faces that are deliberately chosen to include difficulties such as rot, non-circular shape, uncentered pith and dirt. The images are taken with a regular digital camera in sawmill environments. Both presented methods use local orientation and Hough transform to detect the pith position, but two different ways to compute the local orientation are used. The results are promising for both methods. At least one of the methods is fast enough to use on-line at a sawmill.