Thickness Measurement of Biocement Covers in Stone During Rehabilitation Works Using Photogrametry and Tomography

Abstract Microbiologically induced carbonate precipitation (MICP) consists of using urease producing bacteria to promote the precipitation of calcium carbonate. This technique has been proposed as an alternative to traditional rehabilitation techniques for stone or masonry old buildings and monuments. The measurement of the small thickness of the biocement precipitated (less than 1 mm in many cases) is a challenge. Although it is possible to obtain models of these surfaces and establish comparisons, the reliability of the measured values in absolute terms is not known. The feasibility of using a mobile phone and Structure from Motion photogrammetry (SfM)-based mobile phone application called Eyescloud3D to measure the thickness of the biocement layer precipitated was investigated. The accuracy of the thickness computed using this method was validated through tomography analysis.