Curvilinear-tree-ring measurements in archaeological wood samples from X-ray computed tomography

In this paper X-ray computed tomography imaging data is used to perform nondestructive tree-ring width measurements in three archaeological wooden samples. Measurements of the curvilinear-tree-ring widths are performed using two approaches: firstly, measuring manually the distance between two points on two consec-utive tree-rings along two orthogonal radii and, secondly, using a recently proposed computational approach which averages all calculated pairwise radial distances between two consecutive tree-rings along the whole tree -ring profile. The results show that the irregularity of the tree-ring shape is an important factor to be considered in performing curvilinear-tree-ring measurements. For irregular shaped tree-rings, deviations up to 1.15 mm were observed between the output of both measurement's approaches. It is concluded that tree-ring width measure-ments along only two orthogonal radial rays are not always accurate enough and therefore averaging along the whole tree-ring profile is recommended.