Figure 4

Visualization of PC1. (a) and (c) show frontal view of transformation determined by the first PC. The top is in the positive direction. The bottom is the negative. (b) and (d) are the same, but for the right lateral view. Green circles represent the average location of landmarks in the entire, superimposed data set. The black lines are links to aid visualization. The red line segments represent the coefficients for each coordinate of each landmark specified by the first PC magnified by a factor of 100 to emphasize the pattern of variation. That is, the red lines indicate the path (direction and relative magnitude) of the landmarks as they change location and move along the specified PC in the indicated direction. The ends of the line segments in the images on the top row indicate the positions of the landmarks at a point 100 units out in the positive direction on PC1. The bottom row is the same for 100 units in the negative direction.