Study of optical tag profile of the tag recognition measurement system in cultural heritage

This study exposes the process to identify the optimum optical tag profile to be used for monitoring the minimum relative displacement of two areas of the artwork. The purpose is to realize an efficient, precise, and accurate structural monitoring system with minimal invasiveness. In particular, it is designed to determine the enlargement of a crack on a fresco inside a closed environment, such as inside a church. Theoretical studies and measurements in a controlled environment are performed to identify the best mathematical distribution to be used as tags. The two small adhesive tags are the main components of the system, they are attached on the surface of the artwork and the acquisition of their images is performed through a high-resolution camera. An advanced least-squares fitting of quadratic curves and surfaces algorithms for the objective function are used to detect the relative distance between these optical tags. The appropriate parameters for monitoring potential cracks on cultural assets are determined with a fitting algorithm of an objective function. In this study, different bi-dimensional objective functions are considered to identify the best configuration.