Yau & Duffy Yau & Duffy
In this paper, the authors outline a technique for animating a face which gives a more realistic texture than most facial animation systems. Their technique involves taking images of a real face and projecting them onto the surface of a 3-D object. This method is aimed at overcoming the problems with facial animation systems which give images that look more like cartoon characters than humans.
The 3-D model was created using a structured light striping technique. The resultant co-ordinate data was triangulated, giving 450 polygons to represent the face. The topology of the data is recorded using an edge list which contains pointers into a list of all the data points. These polygons do not change as far as their connectivity goes, just the positions of the points are changed through transformation matrices.
Two 3-D models are used in this animation system. One of them is dynamic and is used to find out the positioning and movements of the face. It is used just before output to the screen to set up the transformation matrix. The second model is static and has the texture mapped onto it. This method speeds up the mapping process before the image is transformed and the lighting calculations take place. The problem with this method is that mapping an open mouth onto a closed mouth looks pretty silly. The authors get around this by having some basic facial movements included with the (semi) static model. These are used in cases when the mouth and eyes go through major movements.
The system is quite slow and restricted, but can give some very realistic results. More flexibility will come as more movements can be made in the static model.
Synopsis by Valarie Hall