High Art: Visualising Damage on a Heritage Ceiling

Photographic survey techniques were employed to monitor the condition of the paintwork on the ceiling of the Queen’s Staircase at Hampton Court Palace. Illumination was provided by a flash, mounted on an 8 metre telescopic mast, raised to approximately 60 cm below the ceiling, with images were taken from a fixed camera position on the floor of the landing. The photometric stereo method was applied with images from ten lamp positions, to calculate surface normals and a depth map. Cross-sections at the estimated surface resolution of 7.7 pixels/mm, achieved a depth (Z axis) resolution of approximately 100 microns.