3D digital image correlation system for monitoring of changes induced by RH fluctuations on parchment

One of the most common sources of damage in Cultural Heritage Objects (CHO) such as parchment, oil paintings and historical textiles is relative humidity (RH) changes which cause inplane and out-of-plane displacements of their surfaces. The best suited method which enables full-field, non-contact displacements measurement with high resolution and sufficient range, is 3D Digital Image Correlation (3D DIC). However, the standard version of DIC requires applying random, good contrast speckle pattern at a surface of the object under investigation. Such requirement is not acceptable for CHOs. In this paper, we analyze the possibility to apply 3D DIC method for monitoring of displacements in selected groups of CHOs without modifying their surface i.e. based on their natural texture. The selection of the data capturing conditions and analysis parameters can lead to successful non-invasive monitoring of CHOs’ behavior. The samples studied herein are historical parchments subjected to controlled RH changes that impose inplane and out-of-plane displacements variations in time