title: Expression-invariant representations of faces.
abstract: Addressed here is the problem of constructing and analyzing expression-invariant representations of human faces. We demonstrate and justify experimentally a simple geometric model that allows to describe facial expressions as isometric deformations of the facial surface. The main step in the construction of expression-invariant representation of a face involves embedding of the facial intrinsic geometric structure into some low-dimensional space. We study the influence of the embedding space geometry and dimensionality choice on the representation accuracy and argue that compared to its Euclidean counterpart, spherical embedding leads to notably smaller metric distortions. We experimentally support our claim showing that a smaller embedding error leads to better recognition.
authors.affiliation: Department of Computer Science, The Technion--Israel Institute of Technology, Haifa 32000. alexbron@ieee.org
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Bronstein
authors.forename: Michael M
authors.initials: MM
authors.lastname: Bronstein
authors.forename: Ron
authors.initials: R
authors.lastname: Kimmel
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D003198:Computer Simulation; D005145:Face / Q000033:anatomy & histology*; D005149:Facial Expression; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D008954:Models, Biological; D010363:Pattern Recognition, Automated / Q000379:methods*; D013382:Subtraction Technique; D014741:Video Recording / Q000379:methods