Maximizing the value of photogrammetric surveys in the conservation of wall paintings

In the field of wall painting conservation, photogrammetric surveys are an increasingly common documentation tool. The outputs from these surveys, including captured images, orthophotos, and three-dimensional models, are used by conservators to monitor and record condition phenomena and conservation treatments. To serve these conservation needs, the outputs should have visual fidelity, meaning they are a close representation of the subject based on their spatial resolution, overall focus, even lighting and color accuracy. However, wall paintings present unique technical challenges for photogrammetry considering their often large scale, irregular topography, range of surface attributes, and access issues. As a documentation technique more commonly applied to capture the geometry of buildings and objects, using photogrammetry to record both the topography and fine surface details of a wall painting requires thorough planning. This paper examines specific challenges in documenting wall paintings and how collaboration between conservators and heritage-recording specialists has improved practice and maximized the value of photogrammetric surveys for conservation.