| 摘要 |
<p>A visual fixpoint marking of the light type (4, 12) is completed by an underlying marker (2) of the "subterranean" type, the electric or magnetic axis (a) of which intersects the ground or road surface in the visually marked fixpoint (C). The visual marker element (4, 12) may disappear or get displaced, but the fixpoint marking will then be easy to reestablish, viz. by locating the axis (a) of the subterranean marker by means of a search detector and remounting the visual marker element (4, 12) in accordance with the refound location of the fixpoint (P.C). The lower marker (2) is arranged so as to remain non-influenced of the upper marker element being removed or laterally displaced.</p> |
