Application of digital techniques in monument preservation

Health records for monuments are produced to provide a basis for scientific monitoring and planning of restoration work. The collected data (locations of deterioration, and architectural and historical archives) must be referenced in a single documentation platform to establish a detailed diagnosis of the state of degradation of the monument. This paper presents the application of digital techniques for production of a health record of a monument, applied to the castle of Chambord (Loire Valley, France). The first step is to provide a 3D digital reconstruction of the monument. This 3D modelling consists in constructing a finely refined and relevant graphic base to spatially reference all data acquired during the project. Topography is used to precisely locate the relative position of the main architectural components, while photogrammetry can set in detail each of these elements. The application of textures extracted from pictures on surfaces of the 3D model provides a realistic appearance. Additional data from a laser scanner can be included to detail complex forms or specific degraded areas for monitoring or documentation purpose. The state of deterioration of the structure is evaluated through a visual in situ survey. Dating and identification of rocks are determined by searching in the historical and architectural archives that are sometimes incomplete. Finally, the NUBES web-based platform is used to spatially associate data with the 3D model of the monument. This database underpins the health record of the castle of Chambord.