1. A method for determining the orientation of a pattern on the surface of an object relative to the object, wherein the pattern comprises an array of generally perpendicular grid lines intersecting at grid junctions, and said object comprises a marker located at an edge thereof, the method comprising the steps of: determining the directions of said grid lines relative to the direction of the reference coordinate system; determining the direction of object's orientation axis relative to the direction of the reference coordinate system; determining the orientation of said grid lines relative to said object's orientation axis; wherein said step of determining the direction of object's orientation axis comprises the steps of determining a location of the geometrical center of the object in said reference coordinate system and detecting and determining a location of said marker in said reference coordinate system.