1. A method of stationing an unleveled optical total station, the method comprising: placing the unleveled optical total station at a first station; at the first station, determining positions of at least three non-collinear measurement points in an instrument coordinate system using the unleveled optical total station; obtaining positions of the at least three non-collinear measurement points in a local coordinate system; and computing a transformation between the instrument coordinate system and the local coordinate system using the positions of the at least three non-collinear measurement points in the instrument coordinate system and the positions of the at least three non-collinear measurement points in the local coordinate system.