A method comprises moving a robotic structure to a first pose such that an end-effector of the robotic structure has an absolute position comprising an absolute location and absolute orientation. The method comprises providing a calibration artefact on the end-effector. The method comprises determining at least three planes coinciding with at least three respective surface planes of the calibration artefact, by measuring absolute locations of a plurality of points on the calibration artefact. The method comprises determining the absolute location and absolute orientation of the end-effector, when the robotic structure is in the position based on the determined at least three planes. The method also comprises calibrating the first pose of the robotic structure using the determined absolute location and absolute orientation of the end-effector.