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 3a shows the error landscape (minimum shown as a peak) for the change in fixation point, 3c the plot for translation along line of sight and 3e 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.