Laser Scanning Techniques for Remote 2D Hyperspectral Imaging of Decorated Monumental Surfaces

Laser scanning prototypes, formerly developed in active remote sensing systems (such as fluorosensor lidar), have been specialized for high resolution multispectral applications suitable to be used in the characterization of large surfaces relevant to monumental cultural heritage.

A LIF (laser induced fluorescence) scanning system, capable of collecting 2D monochromatic images acquisition on up to 90 different spectral channels in the visible/UV range has been developed to investigate the presence and the aging of consolidants as well as the occurrence of bio degradation. Data processing software, based on SAM (spectral angle mapper) and PCA (principal component analysis) has been implemented to extract the information relevant to conservation strategy and to best visualize damaged areas in suitable false color combinations of the collected images. Data bases relevant to pigments, consolidants and bio-degrading agents have been built for Cultural Heritage materials on different substrates (e.g. plaster, ceramics, wood).

The original point scanner has been recently replaced by a line scanner which, once properly matched with the CCD detector, allowed for increasing of more then two order of magnitude the data acquisition speed.

Examples of data collected during recent field campaigns on fresco’s (up to 12 m distance) and painted wooden artifacts will be presented. Results relevant to preliminary laboratory investigations on stones and mosaics aimed to ascertain both the provenance and the degree of conservation of the materials will be also presented.