This type of measurement examines the change in observed profile shapes. Convergence measurements are taken during the construction or reconstruction of subterranean works, e.g. tunnels, sewers, subways (or other subterranean pathways), drifts, manholes, and holes. They can be also used in the reconstruction of subsurface structures, e.g. shops and churches. Convergence measurements are used as a basis for documenting the impact of building activities on a measured object, for producing expert opinions, for operational management, etc.