Can hyperspectral imaging be used to map corrosion products on outdoor bronze sculptures?

Abstract

The application of hyperspectral imaging in the field of cultural heritage investigation is growing rapidly. In this study, short wavelength infrared hyperspectral imaging (960–2500 nm) has been explored as a potential non-invasive technique for in situ mapping of corrosion products on bronze sculptures. Two corrosion products, brochantite and antlerite, commonly found on the surfaces of outdoor bronze monuments, were considered. Their spatial distribution was investigated on the surface of the bronze sculpture The Man with the Key by Auguste Rodin in Oslo. The results demonstrate that hyperspectral imaging combined with image analysis algorithms can display the distribution of the two corrosion products in different areas (unsheltered and partially sheltered) of the sculpture.

Combination of noninvasive imaging techniques to characterize pigments in Buddhist thangka paintings

“…In the thangka under investigation, if some zones could be attributed easily to azurite, such as the halo of the main deity, some blue/greenish areas presented more complex spectra, probably originating from mixtures of Cu-compounds (figure 6b). In particular, it is possible to identify basic copper (II) sulfates, brochantite [Cu 4 SO 4 (OH) 6 ], and antlerite [Cu 3 SO 4 (OH) 4 ]: according to [22] , the brochantite SWIR spectrum shows a peak at 2334 nm, and antlerite is characterized by a doublet at 2304 and 2352 nm. Brochantite has been identified in thangkas by Duffy and Elgar [6] , but mixed with malachite in green zones.…”

Near-infrared modeling and enhanced visualization, as a novel approach for 3D decay mapping of stone sculptures

“…Near-infrared (NIR) imaging is a specialized photography technique which has been highly associated with archaeological investigations, mainly regarding the polychromy of paintings (Delaney et al 2016;Vandivere et al 2019) and sculptures (Sfarra et al 2014;Gasanova et al 2018). NIR imaging has also been explored to recognize corrosion on stone architectural heritage (Lerma et al 2000;Lerma et al 2012), and bronze sculptures (Catelli et al 2018). The recent introduction of digital cameras employing CCD (charge-coupled device) and CMOS (complementary metal-oxide-semiconductor) sensors, modified for near-infrared or full-spectrum imaging (coupled with external NIR filters) has made high-resolution NIR imaging more feasible.…”

Review of Methods for Documentation, Management, and Sustainability of Cultural Heritage. Case Study: Museum of King Jan III’s Palace at Wilanów

“…However, the scope of information possible to obtain increases if the spectral information is combined with 3D shape reconstruction. The integration of spectral and geometric data was a subject of many works [17,40,83,[138][139][140][141][142]. Nevertheless, this issue remains a challenge in the near future.…”

“…SWIR region may be applied in the monitoring of the degradation of painting materials [143]. Multispectral imaging has also been successfully applied in documentation of parchment degradation [144,145] and the analysis of pigment discoloration [140,146] used hyperspectral imagery to map corrosion products on outdoor bronze sculptures.…”