Alan WATT An abstract muscle model For three dimensional facial animations

muscle-based model – The abstract muscle-based model has been developed by Waters in 1987. This model is based on a coarse anatomic model due to the fact that 18 the deformation of the polygon mesh (equivalent to the skin) is made through two types of abstract muscle. The linear muscle, which pulls the mesh, is represented by a point of attachment and a vector. The sphincter muscle, which squeezes, is represented by an ellipse. Neither of them are connected to the polygon mesh and their action is defined by an influence zone. The advantage of this technique is that the system of mesh modification is independent of the topology of the face. The muscle abstract musclebased model is also used in conjunction with B-Spline patches by Carol Wang to animate a face (Figure 7). This face is controlled by 46 muscles, 23 for each side. Figure 7 Taken from [CWww]: Abstract muscle-based model to control B-Spline patches : Expression of a) sadness, b) smirk, c) fear and d) disgust. A more detailed description of the Abstract muscle-based model will be given in the next section. 4 The abstract muscle-based model This whole section is dedicated to the abstract muscle-based model due to the aim of the project, which is to study the qualities and defaults of this model to produce 3D facial animations. The abstract muscle-based model, first reported in 1987 by Waters [KW87], is one of the most popular models nowadays. It is based on facial anatomy due to the fact it uses