Introduction of Accessorial Sketch Features for the Automatic Conversion of Mechanical Sketches into 3D Models

Introduction. Sketches in the form of line drawings are commonly observed in magazines, books, manuals, etc. Sketches are also important for designers, especially mechanical designers, when they invent new ideas of products and their parts. The automatic conversion of sketches into 3D models will be advantageous for several applications. For example, it is expected that robots will be able to understand sketches by their converted 3D models in the future. In the last fifty years, numerous methods to automatically convert sketches into 3D models have been considered and developed. However, no real system for the conversion has been developed till now. We have been developing methods for the conversion of sketches into 3D models for approximately eight years. Consequently, we proposed a method as SFBCM (Sketch Feature-Based Conversion Method) to achieve this conversion [10-11]. In SFBCM, many issues have been still remained for developing the practical conversion system. In this paper, we attempt to handle chains, springs and screws in SFBCM. Generally, they are important machine elements, and often used in mechanical products and their parts. However, their sketches are tend to become symbolic because their shapes are complex. Fig. 1 shows examples of the sketches. Fig. 1(a) shows a sketch of chain. Fig. 1(b) shows a sketch of spring. Fig. 1(c) shows a sketch of screw with a hexagon head. In this paper, Accessorial Sketch Features (ACSFs) are introduced to SFBCM for handling sketches of chains, springs and screws. Generally, the shapes of them contain many kinds of repetitive features, so we define ACSFs from them.