Efficient Free-Form Contour Packing Based on Code Matching Strategy

Abstract

Freeform surfaces exist widely in the stock cutting process of clinical prosthesis preparation, aviation, ship, and other manufacturing industries. The free-form contours of surfaces need to be packed before they are machined from raw materials. The existing methods search a contour position by rotating the contour and translating it to connect other contours for packing. The relative position between two contours will be changed after the rotation as the contour description is lack of geometric invariance. These methods easily miss the best layout position resulting in interspaces in the raw material. Moreover, this result seriously reduces the performance and efficiency of an automatic packing system. Therefore, a new packing algorithm is proposed in this paper by combining the geometric invariant description and coding matching for contours to solve the contour rotating and position connecting problems. The optimal position of a contour can be found directly and then connected by the extracted similar complement features of the contour. The experimental results show that the proposed method can greatly improve quality and efficiency of the layout, especially in the material utilization. INDEX TERMS Computer graphics, code matching, shape, free-form contour packing, freeman chain code, geometric invariant description, layout.

Dental Restorations Packing Based on the Contour Similar Features Matching and Collision Strategy

“…The experimental results verify the previous hypothesis, our algorithm can solve the packing problem of dental restorations well. But we find that the algorithm has a little flaw, when there are several large packing contours, the positioning algorithm based on the Principal Component Analysis Methodology [18] will make the contour beyond the outer boundary of the raw material. However, for a few larger contour's examples, our algorithm can simultaneously improve the packing utilization and efficiency.…”

“…However, the end face projections of the dental restorations are very complicated free-form curves. The small missed angle will be gradually enlarged in the subsequent rotation [18]. The shape of restorations is complex.…”

“…The time complexity and space complexity of NFP are exponentially related to the number of edges of the polygon. In addition, restorations have many non-convex features, therefore, it is a great challenge to apply the NFP algorithm in dental restoration packing problems [18].…”

Two-dimensional irregular packing problems: A review

“…This method can solve the problem of any non-convex polygon, and be still applicable to any geometry with holes, and the method is stable in numerical stability. Guo (Guo et al, 2019) proposed a placement strategy based on curve coding and feature matching. This is a new placement strategy based on curve similarity feature matching.…”

A Block Corner-Occupying Heuristic Algorithm for Constrained Two-Dimensional Guillotine Cutting Problem of Rectangular Items

“…In industrial production, for instance, the cutting of sheet metal, glass, and plywood, two-dimensional cutting problem often occurs. Good cutting pattern can improve the sheet utilization and reduce production cost [1]- [5]. Two-dimensional cutting problem can be regular or irregular cutting problem, constrained or unconstrained cutting problem, guillotine or non-guillotine cutting problem, depending on the item geometry, constraint on upper bound frequency of item, and cutting process, respectively.…”