1. An apparatus for determining at least one orientation parameter of an elongate object having a tip contacting a surface at a contact point, said apparatus comprising: a) a projector on said elongate object for illuminating said surface with a probe radiation in a predetermined pattern from a first point of view; b) a detector on said elongate object for detecting a scattered portion of said probe radiation returning from said surface to a second point of view; c) a unit for determining said at least one orientation parameter from a difference between said probe radiation and said scattered portion.