For each hem-edge point measurement you want to make, you must probe two points:
- The first point
must be located on the nearest surface of the CAD model. This sets the nominal plane and direction used to calculate the position of the hem edge point. - The second point
must be located on the edge itself. It is projected onto the nominal plane 
to determine the actual position of the hem edge 
.
The total deviation 
from the nominal position 
is calculated from the two partial deviations.
