Measuring the Information Content of Fracture Lines

Reassembling unknown broken objects from a large collection of fragments is a common problem in archaeology and other fields. Computer tools have recently been developed, by the authors and by others, which try to help by identifying pairs of fragments with matching outline shapes. Those tools have been successfully tested on small collections of fragments; here we address the question of whether they can be expected to work also for practical instances of the problem (103 to 105 fragments). To that end, we describe here a method to measure the average amount of information contained in the shape of a fracture line of given length. This parameter tells us how many false matches we can expect to find for it among a given set of fragments. In particular, the numbers we obtained for ceramic fragments indicate that fragment outline comparison should give useful results even for large instances of the problem