Applications - 3D Face Modeling, Analysis and Recognition - page 175

Figure 5.12 Examples of intraclass (same expression) geodesic paths with shape and mean curvature
mapping between corresponding patches

Figure 5.13 shows geodesic paths between patches of different facial expressions. These
geodesics are termed interclass geodesics . Unlike the intra-class geodesics shown in Figure
5.12, these patches deform in a different way.

Feature Vector Generation for Classification

To classify expressions, we build a feature vector for each facial scan. Given a candidate facial
scan of a person j , facial patches are extracted around facial landmarks. For a facial patch P j ,
a set of level curves

j are extracted centered on the i th landmark. Similarly, a patch P ref is
extracted in correspondence to landmarks of a reference scans ref . The length of the geodesic
path between each level curve and its corresponding curve on the reference scan are computed

i

{ c λ }