1. A method of reducing the number of parameters which must be conveyed to a decoder to animate an object, comprising the steps of: identifying at least one defining parameter which defines the animation of a portion of an object, identifying at least one derived parameter which can be interpolated from said at least one defining parameter, specifying interpolation functions which enable respective ones of said derived parameters to be interpolated from said at least one defining parameter, and arranging said parameters in a data structure which includes the identities of said at least one derived parameter and said at least one defining parameter and which indicates from which of said defining parameters each of said derived parameters can be interpolated, said interpolation functions and said data structure when conveyed to a decoder enabling said decoder to interpolate said derived parameters from said defining parameters and thereby reduce the number of parameters that must be conveyed to said decoder to animate an object.