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FIGURE 8.4 Machine guidance.

recognize an object, and, when the features are found, how should
they be analyzed to decide which object (if any) has been found?

8.4 Robot Vision Locating Position
Humans use several techniques for gauging distances, especially tri-
angulation on the left- and right-eye views, feedback from the eye’s
focusing mechanism, and the apparent motion produced by small
head movements. This kind of object location may make use of
knowledge about the object being located. By knowing how large the
object really is, one can judge how far away it is from the size of its
retinal image.
Few robot-vision systems use binocular vision, autofocus feed-
back, or moving cameras to estimate distances. However, with a rig-
idly mounted camera, it is possible to interpret each visible point as
lying on a particular line of sight from the camera. Accurate informa-
tion about the true distances between visible points on an object
allows the robot-vision system to accurately calculate its distance.
Similarly, if an object is resting on a platform at an accurately known
distance, the robot vision system can interpret distances in the cam-
era image as accurate distances on the object.
However locations are determined, the visual location task for a
robot-vision system normally includes calibration as well as object loca-
tion. Calibration normally is carried out by providing the system with
a view that has easily identifiable points at known spatial locations.