Advanced Techniques for the Studies of Stones and Paintings on Walls: State of the Art and Open Problems

Different imaging techniques are presented and applied to the study of historical and artistic objects and buildings, mainly belonging to Renaissance time, in the city of Bologna, where the arenaria (sandstone) of which they are constituted is largely degradated in the surfaces due to the effects of pollutants present in the atmosphere, since suitable 3D reconstruction algorithm may be very useful in panning restoration works. We based our investigation on multispectral techniques ranging from infrared reflectography, digital thermography and thermal diffusivity (mirage effect) and ultraviolet fluorescence. Possible contributions from ultrasound analysis as well as other non-destructive techniques are addressed. In addition, an original portable equipment based on the detection of Compton scattering photons and a further statistical analysis of the collected data has been utilized.