Close Range Photogrammetry for Measurement of Paintings Surface Deformations

The paper describes the first results about a study on the measurement of paintings surface deformation. The study was carried out using one ancient painting model made in a restoration laboratory and consolidated with the materials and dilutions most frequently used in the field of conservation. The restorers suppose deformations of the paintings surface from 0.1 mm to some millimetre when the painting model is keeping in environment with the presence of humidity and temperature fluctuations. The main purpose of the study is to evaluate the relative accuracy and the reliability of multi-images photogrammetric techniques related to the camera stations network and to the commercial software used. The tests were carried out with two commercial software (i-Witness and CDW) and a digital Canon EOS 1 Ds Mark II camera measuring more than once the coordinates of 143 targets on the painting model. The tests have showed a relative accuracy of about 0.1÷0.2 mm. Some preliminary tests were carried out with the short range laser scanner Minolta Vivid 9i too. The laser scanner techniques, even though having notable potential, demonstrated, however, a series of problems which require further study.