Machine Interpretation of 2D Line Drawings as 3D Solid Objects

In engineering design, much time and effort could be saved if a computer could interpret an engineer's initial concept drawings. This paper describes a prototype system for interpreting line drawings as solid polyhedral objects. It concentrates on four stages of processing: line labelling, identification of parallel lines, inflation to 2 1/2 D, and determination of hidden topology. Although the system is often successful, particularly with simple drawings, there are also cases where the correct interpretation is obvious to a human but cannot be determined using existing algorithms. The paper gives examples both of the successes of the approach and of typical cases where it cannot replicate human skill.