3D Morphable Models are used for face analysis because the intrinsic properties of 3D faces provide a representation that is immune to intra-personal variations such as pose and illumination. Given a single facial input image, a 3DMM can recover 3D face (shape and texture) and scene properties (pose and illumination) via a fitting process.
Each of our face models is created from a set of 3D face scans. Each scan is in the form of a graph, where the vertices are locations on the surface of the face, and the edges connect the vertices to form a triangulated mesh. Each vertex also has a colour; hence the vertices define both the shape and the texture of a face. Each face is registered to a standard mesh, so that each vertex has the same location on any registered face.
The model has two components: (i) a mesh consisting of the mean face, and (ii) two matrices, one each for shape and texture that describe the various modes of variations from the mean. The number of modes of variation depends on the size of the mesh, and also is different for shape and texture. Hence the appearance of a given face can be summarised by a set of coefficients that describe how much there is of each mode of variation.
If you would like to download and use any of the University of Surrey 3D face models, details of their availability are here.
The work of our group on 3D Morphable Models followed on from early work of Blanz and Vetter, and also from the PhD thesis of S. Romdhani. The development has taken place in several phases: