TLS-based 3D Deformation Monitoring of Church Bell Tower Geometry

Unlike traditional methods, terrestrial laser scanning (TLS) enables one to collect enormous amount of data in a fairly short time, consequently reducing field efforts. This backed up the decision to employ TLS for deformation monitoring of the brick bell tower of St. Anthony of Padua Church in Belgrade. One epoch of terrestrial laser scanning completed in March 2015 revealed that the projection of the tower axis vector to the horizontal plane reached the value of almost 1.2 m, that is nearly three times greater than the value observed at the time of the tower completion. This urged for the tower stability monitoring to be started which finally happened in 2019. Over a period of about four and a half years a trend in the tower tilting increase of 1.6 arcmin in total was unequivocally established, that is, the top of the tower displacement of 22 mm in the horizontal plane