The design and animation of digital 3D models is an essential task for many applications in science, engineering, education, medicine and arts. In many instances only an approximate representation is required and a simple and intuitive modelling and animation process, suitable for untrained users, is more important than realism and extensive features. Sketch-based modelling has been shown to be a suitable interface because the underlying pen-and-paper metaphor is intuitive and effective.
In this paper we present LifeSketch, a framework for sketched-based modelling and animation. Three- dimensional models are created with a variation of the popular “Teddy” algorithm. The models are analysed and skeletons with joints are extracted fully automatically. The surface mesh is bound to the curved skeletons using skinning techniques and the resulting model can be animated using skeletal animation methods.
The results of our evaluation and user study suggest that modelling and animation tasks are considerable more efficient than with traditional tools. The learning curve is very flat and a half page document was sufficient to familiarise users with the tools functionality. Users were satisfied with the automatically extracted joints, but some users struggled selecting the appropriate rotation axes and angles for animating the resulting 3D objects. A more intuitive, preferable automatic or sketch-based approach for animations is needed. Overall users were satisfied with the modelling capabilities of the tool, found most of its functionality natural and intuitive, and they enjoyed using it.