Marking Strategies

This overlay video creation system exploits the ability of the human user to quickly mark a sequence of precisely locatable points in the two similar images that guides their alignment. This step is the most difficult for fully automated watermark search systems to achieve with the precision necessary for the identification of idiosyncratic, highly similar, typically artifact-ridden radiographic and photographic images of watermarks. (Rubbings and tracings of watermarks are insufficiently precise for assessing exact matches.) Our marking programs watermarkMarker and watermarkPointMarker provide the user with a simple marking tool that allows the marking to be done in minutes. The subsequent alignment computation and the creation of the overlay video are then rapid on a laptop.

What is a Precisely Locatable Point?

The exact points used to mark any watermark are idiosyncratic to that watermark type. Precisely locatable points may be:

  • points at which chain lines cross certain elements in the watermark
  • sharp points in the watermark
  • points where two wires in the watermark intersect
  • points that can be easily seen and reliably marked in all (or most) of the watermarks of that type

Probably the best way to understand how to do the marking is to look at some of the examples in the Marking Leonardo section below. We have not only marked the points on these watermarks, we have also tried to explain in detail why we chose those particular points, and how to be sure that you have them exactly right.

Marking Leonardo

Thoughout the Leicester and Arundel Codices of Leonardo, there are seven different watermark types (which are represented by more than one example). These are:

Each of the above items leads to a page that presents type-specific templates that describe in pictures and in words how and where to mark the “precisely locatable points.” If you are marking one of these types, use the specified locations. If you are marking a new watermark type you will need to select your own locations thoughtfully.