ShapeShop: Free-Form 3D Design with Implicit Solid Modeling

Implicit modeling has been used since the early 1980s as an alternative to mainstream solid-modeling techniques. Beyond Boolean composition, implicit modeling integrates blending and deformation operators which allow complex free-form solid models to be more easily described. Recent advances have alleviated some of the major technical problems, such as visualization speed and surface control. In this chapter we describe how to combine these new techniques with a sketchbased 3D modeling interface, resulting in a powerful tool for quickly creating solid models. Our system, called ShapeShop, has been used as a testbed to investigate a range of problems, from real-time visualization [36], sweep surfaces [35], surface parameterization [38], and implicit surface deformation [41], to higher-level design and usability issues such as structured visualization [39] and 3D manipulation [40]. Sketch-based 3D modeling is the common thread which ties all these various problems together [33, 34, 37, 46]. Much like the seminal Teddy system [18], ShapeShop is a tool for incrementally creating a 3D model using simple 2D sketches. From this starting point, many other sketch and pen-based interaction techniques have been adapted and integrated into the system. ShapeShop borrows liberally from work in sketching assistance [7, 17], gestural systems [48], crossing interfaces [2], and suggestive modeling [16]. One long-term aspect of the ShapeShop project is to evaluate how these non-traditional techniques can be effectively combined within a complex interface.