An href="module.php?name=Lexikon&file=search&eid=1&query=interpolation">interpolation technique where an href="module.php?name=Lexikon&file=search&eid=1&query=animation">animation program generates extra frames between the key frames that the user has created. This gives smoother animation without the user having to draw every frame. A scene is described by a mathematical model - a set of two- or three-dimensional objects whose positions in are given by sets of coordinates. Tweening uses mathematical formulae to generate these coordinates at a sequence of discrete times. The simplest system would move each point at a constant rate in a straight line between its initial and final positions, though other kinds of path are possible. The coordinates at each time step are used to generate (or "render") a two-dimensional image of the scene which forms one "frame" of the animation. Tweening is similar to href="module.php?name=Lexikon&file=search&eid=1&query=morphing">morphing except that morphing is usually performed by interpolating between corresponding points marked by the user on two images, rather than between two configurations of a model. (1995-04-04)