Method for Quantitative Assessment of Local Deformation Zones of a Brick Facade From Terrestrial Laser Scanning Data

Design documentation for old buildings has largely been lost, so the facade slope measured by terrestrial laser scanning cannot be separated into initial construction deviation, accumulated deformation and local damage. A procedure of internal geometric referencing of point clouds is proposed for assessing local deformations of brick facades without design documentation. Lines in undamaged masonry of the same facade form the reference, and the slope of the studied zones is expressed as a dimensionless localisation coefficient, a multiple of the background level. On a two-storey brick building, the background level was 2.79 mm/m against 28.32–32.01 mm/m in zones adjacent to masonry discontinuities, i.e. a coefficient of 10.1–11.5. For this object, the classification remained stable under the adopted error assumptions. The procedure helps prioritise zones for subsequent opening-up inspection.