Synchronization of the orientation of a 3d measurement device and the orientation of an intelligent guidance device

There is described a method to synchronize the orientation of an IGD 3D Coordinate System and the orientation of a 3DM 3D Coordinate System, in which the IGD's gravity direction measurement device and electronic compass are used explicitly. There is also described how an IGD, once its orientation has been synchronized to the orientation of a 3DM, can be used to display 3D graphics that guide the measurement process.