3D photogrammetric models from HDR images: the case study of the Fontanone Visconteo in Bergamo

The world is a complex subject whose dynamic range between dark and light cannot be captured by digital cameras. The range of light that can be measured and recorded by a single exposure, is too limited and adapted only for the average light values of the scene. This paper focuses on the integrated survey activities undertaken on the Fontanone Visconteo in Bergamo, to improve its knowledge and assess its conservation status. The specific lighting conditions of the environments (in particular, of the tank) have given the perfect opportunity for testing solutions aimed at the reconstruction of the clouds from different HDR processing to highlight the diverse surfaces’ treatment and understand the sequence of build actions. The purpose is to provide a thought-provoking discussion about the delicate issue of high-quality work that can be obtained from HDR images (12 bit) and RAW files such as TIF, DNG, and JPG (8 bit).