Method and apparatus for representing a work area in a three-dimensional structure

Apparatus for representing a work area in a three-dimensional structure comprising:

• a viewing device for sharply imaging a plane of the work area;
• measuring means for determining a position of the viewing device relative to said structure;
• a comparator for comparing position data of said viewing device determined by said measuring means with a set of coordinates of a predetermined path of displacement along a plurality of respective planes in the work area;
• a display unit for displaying an image of one of said plurality of planes in said work area being observed by said viewing device;
• and
• a data memory for storing a set of data for said path of displacement relative to said structure;
• wherein said display unit is responsive to said set of data for providing an image of a piercing point for the plane of said work area currently being observed by said viewing device, said piercing point being shown in its correct position along said path of displacement.