Interactive control of interpolations for an-imation and modeling

Most animation systems based on key-framing require the animator to define a multitude of curves to describe the evolution of parameters such as position, orientation, curvilinear abscissa, color as functions of time. On top of having to input a large number of data, the animator cannot easily estimate the relationships between all these curves. The aim of this paper, is to spare him the separate description of all these curves. In another paper, we presented a scheme making the interactive control of orientation interpolations possible. This scheme is now extended in order to allow the interactive control of both orientation and position curves. Furthermore, we present a new scheme allowing the automatic parametrization of such mixed curves. It provides a parametrization giving acceptable results, without the intervention of the animator. However, the animator has the possibility to modify this parametrization by specifying additional constraint. The parametrization is based on an optimization process. Such an interactive animation system has been used for the interactive design of sweep objects, i.e. objects constructed by moving a contour along a curve.