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5 Expected behaviour of fixation measure

 

In this section an analysis is made of the idealised behaviour of the error signal in response to movements of a sensor, with six degrees of freedom, relative to a known object, again a simple circle. The movements to be analysed are as follows,

Foveal fixation
The change of the point of fixation in a grid of points covering the object.
Distance to object
Movement along the line of sight with a constant, central fixation point.
Object rotation
Movement of the sensor around the object retaining a constant fixation point and distance. Equivalent to rotating the object.

The above categories cover all the movements required for an animate system to position itself in a learned viewpoint relative to a known object. This type of behaviour pervades the animal kingdom irrespective of the level of intelligence, as a means of providing the animal with the best available information as a basis for further behaviour or recognition.

Figure 3 shows the behaviour of the error signal as a result of the three types of movement. Figure 3 a shows the error landscape (minimum shown as a peak) for the change in fixation point, 3 c the plot for translation along line of sight and 3 e the rotation of the object. In the next section this expected behaviour, for a simple synthetic object will be compared with the behaviour of more complex, real world objects in a laboratory environment.



Next: 6 Experimental behaviour of Up: A fixation and viewpoint Previous: 4 Control theory applied

Rupert J Young
Mon Jul 7 17:45:52 BST 1997