This chapter describes a pen-based modeling system for the styling design of 3D objects. Our system is tailored toward the rapid and natural design of styling features such as freeform curves and surfaces. In a typical scenario, the user begins by constructing the base wireframe model of the design object. For this, the user first sketches the initial feature curves on a very rough and simplified 3D template model. This template model acts as a platform that helps anchor users’ initial strokes in 3D space. Once the initial curves comprising the wireframe are constructed, the base 3D template is removed, leaving the user with a set of 3D curves. Next, through direct sketching, the user modifies the initially created curves to give them the precise desired form. After the desired wireframe is obtained, the user constructs interpolating surfaces that cover the wireframe. Finally, using two physically-based deformation tools, the user modifies the newly created surfaces to the desired shapes. Once the basic wireframe and surfaces are created, further details can be added using the same strategy of curve creation, curve modification, surface creation, and finally surface modification.
Levent Burak Kara, Kenji Shimada. (2011). The Creation and Modification of 3D Models Using Sketches and Curves. Sketch-based Interfaces and Modeling, pp 341-367, 2011, Springer London.