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boss, a large eminence on the left frontal bone of human juveniles, the
center of which can be considered a “fuzzy” landmark. Due to their
nature, placement of fuzzy landmarks on an object may require multi-
ple data collection episodes with the average of the coordinates from
several data collection episodes being used for analysis.
c) Constructed landmarks:
Constructed landmarks are points corresponding to locations that are
defined using a combination of traditional landmarks and geometric
information. Oftentimes, there exist surfaces of interest that are void
of traditional landmarks and fuzzy landmarks. In this instance, land-
Figure 2.5. Two constructed landmarks shown on a human hip bone. The first is con-
structed by locating two traditional landmarks, the anterior superior iliac spine and
the posterior superior iliac spine (marked by open circles) and connecting these land-
marks by a line that follows the arc of the iliac crest. The midpoint of this arc (shown
as a filled circle) is recorded as a constructed point. The second constructed point is
located by drawing two lines at right angles to each other across the acetabulum (sock-
et for the ball of the femur), one line measuring the width of the acetabulum, the other
measuring the height. The intersection of these lines cross on the acetabular surface is
recorded as a constructed point.
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