1. Apparatus for detecting tunnel convergence; comprising: at least one platform including at least one scanning device that is configured to acquire 3D point cloud data of an interior of the tunnel; a processor that: determines a set of one or more indicators from 3D point cloud data for the tunnel acquired at a first time; identifies the set of one or more indicators in 3D point cloud data for the tunnel acquired at at least a second time; amalgamates the sets of one or more indicators; compares the indicators in the amalgamated sets at the first and at least second times; and outputs a result indicative of a change or no change in one or more indicators since the first time.