Thermal displacement mapping for detecting thermal expansion of heritage building during heatwave using 3D laser scanning

The measurement of displacement is an essential factor in evaluating the stability of a heritage structure, especially when it is old. An unprecedented heatwave occurred in the summer of 2022 in the UK and 3D laser scanning was applied to monitor the more than 130-year-old Victoria Gallery and Museum (VG&M) to monitor the heatwave effect in this paper. In this paper, thermal displacement mapping was proposed, and the overall thermal expansion behaviour of VG&M was identified through thermal displacement mapping. The separate displacement calculation (SDC) method was proposed to eliminate the error caused by the registration of the point cloud when calculating the thermal displacement. The behaviour of thermal displacement mapping was analysed along with the movement of the sun, and the maximum displacement when a heat wave occurred was 8.9 mm. In particular, when the heat wave came, the maximum thermal displacement expanded from the upper center of VG&M to the left and right.