Abstract: A method comprises detecting at a plurality of light-receiver units, an impingement position of the light plane on a photo sensor that has a known relative position in relation to the surface, determining, for each light-receiver unit and based on the impingement position and the known relative position, a crossing position value of the light plane with respect to the surface, performing a combined analysis of the crossing position values from the plurality of light-receiver units to derive alignment information comprising the deviation of the alignment of the surface of the structure relative to the light plane, and displaying the alignment information to a user. The invention also relates to computer programme product, a light-receiver unit and a system comprising a plurality of light-receiver units for performing the method.

Abstract: A surveying instrument for executing a relocation functionality, which determines first coordinates of a stationary target point associated with the start signal, in response to a start signal, a first actuator and a second actuator are controlled such that the stationary target point remains within a detection area of a tracking unit of the surveying instrument, determines second coordinates of the stationary target point, receives an end signal, wherein the second coordinates of the stationary target point are associated with the end signal, and based at least in part on the first and second coordinates of the stationary target point, and determines a relative pose of the surveying instrument with respect to a first setup location and a second setup location, wherein the first setup location is associated with the first coordinates and the second setup location is associated with the second coordinates.