Visual Analytics Approach On Exploring Grotto Wall Painting Degradations Spatiotemporal Patterns

For preserving the grotto wall paintings and protecting these historic cultural icons from the damage and deterioration in nature environment, a visual analytics framework and a set of tools are proposed for the discovery of degradation patterns. The framework is designed based on the traditional hypothesis testing methodology of cultural heritage conservations and restorations. It integrates a customary work-flow with an iterative observation-hypothesis-investigation process. In comparison with the traditional analysis methods that used restricted scales, our method provides users with multi-scale analytic support to study the problems on site, cave, wall and particular degradation area scales, through the application of multidimensional visualization techniques. A multi-scale visual analytics framework is proposed and several hypothesis testing tools are developed for assistance of cultural heritage domain experts' work, including a radial layout plus bar charts tool for the overall visualization at site scale, an aggregated visualization tool with line charts combined with Radar maps to explore the overall and detailed degradations in various scales, a matrix visualization tool to study the correlations, and a semi-automatic glyph and space syntax based tool to support the degradation illustrations, which is not only compatible with the domain experts' working experiences, but also performs a good efficiency. A ThemeRiver based temporal investigation tool is also developed. Several case studies have been carried out using real-world wall painting data collected from a renowned World Heritage site, to verify the usability and effectiveness of the proposed method. User studies and expert reviews were also conducted through by domain experts ranging from scientists such as microenvironment researchers, archivists, geologists, chemists, to practitioners such as conservators, restorers and curators.