Integrating spatial and spectral information for enhancing spatial features in the Gough map of Great Britain

• Published in: Journal of cultural heritage Vol. 34; pp. 159 - 165
• Main Authors: Dorado-Munoz, Leidy, Messinger, David W., Bove, Damien
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.11.2018
• Subjects: Gough map; Nearest-neighbor diffusion; Pan-sharpening; Spatial enhancement; Spatial enhancement; Gough map; Pan-sharpening; Nearest-neighbor diffusion
• ISSN: 1296-2074; 1778-3674
• DOI: 10.1016/j.culher.2018.04.011

•Hyperspectral images (HSI) of the well-known Gough map or Britain are the main data used in this project.•Some artifacts of the map such as handwriting texts are illegible despite the decent spatial resolution of the HSI.•A method called Pan-sharpening, previously used in remote sensing field, is introduced here to the cultural heritage community. The Pan-sharpening process improves the spatial resolution of the HSI without losing spectral fidelity. The spatial sharpening is performed by integrating the HSI with high spatial resolution digital images that are available for the Gough map.•Because the spectral resolution of the HSI is practically the same after the Pan-sharpening, transformation methods used in hyperspectral processing are applied to the pan-sharpened data in order to get complimentary results where spatial features are enhanced.•Enhancement of particular details of the map and faded text are shown in the paper as examples that the proposed methodology works. The Gough map has been recognized as the earliest surviving map of Great Britain. The map, dated to late 14th or early 15th century, depicts many and sophisticated cartographical local details, which was unusual in European medieval maps. Moreover, the rewriting and re-inking of some names or areas could indicate the map was re-touched after its original production. The Gough map, today with restricted access and in a conservation environment, was displayed for some time at the Bodleian Library in Oxford, where it was frequently in contact with scholars. Despite this familiarization, the Gough map has not been widely researched and inquiries about the original purpose of the map or the context in which it was made remain unknown. Recent interest in the map has lead to the use of new technologies to image the map and produce sophisticated data that allows scholars and scientists to examine it taking advantage of the new information. In this paper, a technique for Pan-sharpening hyperspectral images (HSI) is introduced to the cultural heritage community. The Pan-sharpening process is applied specifically to HSI images of the Gough map of Great Britain with the purpose of using relatively low spatial resolution hyperspectral analysis techniques on its very fine features. The Pan-sharpening technique is based on Nearest-neighbor diffusion (NNDiffuse) and the spatial enhancing is aimed at faded features such as handwriting and some distinctive details that are only visible in high-resolution conservation photographs. It is shown here that the use of the NNDiffuse Pan-sharpening improves spatial features in HSI of historical artifacts without impacting the spectral fidelity, and that the findings in the analysis of these features could contribute to the understanding of the Gough map and its importance in the historical context of Great Britain.