1. A method of forming an interpolated image corresponding to a given temporal distance ratio between a first and a second image, the first and second images each including a first and a second 3-D shape model of an object having respective shading values and there being a 3-D motion vector defining the transformation between the first and the second 3-D shape models, said method comprising the steps of: a) adjusting the 3-D motion vector to obtain an interpolation 3-D motion vector; b) forming an interpolation 3-D shape model from the interpolation 3-D motion vector and either the first or the second 3-D shape model; and c) forming an interpolation image from the interpolation 3-D shape model and the image shaping values from the first and second 3-D shape models.