Based on the study of retrieving plane geometric figures (PGFs) in the area of computer aided instruction, a feasible solution for PGF retrieval is proposed. The authors focus on several challenging tasks such as sketch beautification, geometric primitive detection, salience analysis of the overlapped primitives, structural
relationship description between two geometric primitives, and figure similarity computing. Several algorithms are presented especially on layout description and complex shape matching. The PGFs are applied directly to content retrieval and compensate for the weaknesses in describing the query intentions using keyword-based search. Experimental results demonstrate the feasibility and significant performance of the proposed retrieval algorithm.