Abstract: The present invention overcomes the disadvantages of the related art by providing a spatial reference system that includes at least one artifact assembly. The artifact assembly has a measuring bar assembly including an inner member with a proximate end and a distal end, an outer member with a proximate end and a distal end, and a compensating member with a proximate end and a distal end operatively disposed between said inner and said outer members. The distal end of the outer member is fixedly mounted to the distal end of the compensating member. The proximate end of the compensating member is fixedly mounted to the proximate end of the inner member.

Abstract: A method 500 and an assembly 200 for determining the presence of gaps located between a first portion 240 of a partially assembled apparatus 228 and a second portion 230. The existence and size of the gap may be discerned by use of a wireless gap sensor 309 which is engaged by the portion 230 as it abuts or comes into close proximity with the portion 240. Other methods 400 and 500 may be respectively used to respectively discern the existence and the size of a gap within an assembled vehicle and to measure the deflection of a portion of an apparatus, such as a vehicle.