Sketching in 3D: A beautification scheme

Primary among all the activities involved in conceptual design is freehand sketching. There has been significant effort in recent years in enabling digital design methods that leverage humans' sketching skills. Conventional sketch-based interfaces are built on 2D touch-based devices like sketchers and drawing pads. The transition from 2D to 3D sketch interfaces represents the latest trend in developing new interfaces that embody intuitiveness and human-human interaction characteristics (HHI). In this thesis, a novel screen-less 3D sketching system is described. The system uses a non-contact depth-sensing RGB-D camera for user input. Only depth information (no RGB information) is used in the framework. The system tracks the user's palm during the sketching process and converts the data into a sketch in 3D. Since the generated data is noisy, making sense of what is sketched is facilitated through a beautification process. Beautification of freehand sketches is integral for building robust sketch understanding systems and sketch-based interfaces for Computer-Aided Design (CAD). The beautification of individual segments in a stroke is preceded by segmentation of the total stroke and classification of individual segments. Additionally, the multi-stroke beautification process is used to enable classification of the 3D sketches from various domains. To evaluate the performance of the system, user studies were performed on seven participants for both single-stroke and multi-stroke sketching scenarios.