Homographic active shape models for view-independent facial analysis

This work addresses the problem of face modelling when the available images are taken from different viewpoints other than frontal. Examples of this situation can be found in surveillance systems, car driver images or whenever it is not possible to place a camera in front of the subjects' face. A number of solutions have been proposed in the literature to deal with these images, but in general they need special databases with explicit 3D data or multiple views to allow for its estimation. As opposed to that, we propose a method able to model faces from a single two-dimensional image captured from a generic viewpoint, as long as there are only bounded occlusions (i.e. only those produced by the nose). Taking advantage of the fact that most facial features lie approximately on the same plane, projective geometry is used to link different views. An Active Shape Model constructed with frontal view images can then be directly applied to the segmentation of pictures taken from other viewpoints.