Deformable Face Alignment via Local Measurements and Global Constraints

This chapter will review a particular approach to deformable face alignment coined constrained local models (CLM). The approach leverages the excellent generalisation properties of local appearance representations of parts and the strong global constraints imposed by the geometrical relationships between part locations. We begin by posing CLM in the general context of deformable face alignment, highlighting its similarities and differences with other approaches and motivating its benefits. An overview of the approach is then presented, explicating its various components and touching briefly on the interrelated issues of optimisation, feature representation and geometry regularisation. The following three sections discuss each of these three components in detail. The chapter concludes with a general discussion and directions of future work.