3D Modeling Technique Based On 2D Silhouette Curves And 3D Samples Using Metaballs

This paper presents a method for generating 3D models from 2D silhouette curves and 3D samples rapidly.Traditional sketch-based modeling systems use abstract notions that are too far from the real world, so they are difficult to comprehend and master especially for novices. Our method can generate proper metaballs rapidly taking advantage of medial axis. Firstly, a silhouette curve is converted into a simple polygon. Secondly, the approximate medial axis of the simple polygon consisting of line segments is computed. Thirdly, the system puts metaballs along the medial axis properly. Using the geometrical property of the medial axis, most of the metaball parameters can be approximately calculated in our method easily, and the thickness of the model can be determined interactively. Finally, we optimize the parameters and get the 3D models.In this paper, we detail the algorithms of getting the proper circle and ellipse primitives based on the medial axis and the silhouette curves respectively, and present the difference between using circle, ellipse, superellipse as primitives.We use the result of PowerCrust for modeling from 3D samples. Every inpoleball of PowerCrust is considered as a metaball. By optimizing the parameters of metaballs, we can get nice result.The approach can be used in rapid prototyping, cartoon object modeling and computer animation special effects.