1. A method of generating a principal component analysis model for representing individuals, the method comprising: receiving a plurality of images of individuals and associated co-ordinate data identifying for each image the co-ordinates of points corresponding to predetermined features of said individuals; for each of said images, utilising said co-ordinate data to determine a mesh for each image, said mesh comprising a number of vertices connected by edges, the edges of said mesh dividing each said image into a number of image portions; and generating a principal component analysis model for representing individuals utilising determined variations of the co-ordinates of the vertices of said meshes for said images and determined variations of corresponding image portions of said images, wherein said determination of a mesh for each image comprises generating a mesh wherein the boundaries of facial features in an image lie substantially along the edges of image portions defined by said mesh.