to interpret. The complexity of the images is 
dependent on three parameters:— 
E the camera-to-object distance varies as 
a function of the rotation; 
W the field of view of the returned image 
can be arranged to cover up to 360 
degrees of the intended rotation; 
W the content of the observed field of view. 
As the camera-to-object range decreases and 
dependent on the object of interest, the distortion 
caused by the rotational element of image 
generation becomes more apparent. However, if, 
under such circumstances, the field of view is kept 
as small as possible, suitable images may be 
produced. It can be seen from this that the 
parameters noted above are inter-dependent. 
Therefore, each should be considered before 
attempting to produce pictures that can be viewed 
by humans. 
2.2 Stereoscopic Imaging Using Line-Scan 
Cameras 
Line of symmetry 
   
   
   
      
CONVERGENCE 
Point 
  
STRNDRRD 
TELEVISION 
CRMERRS 
   
Figure 11 Stereo Region for Television Type 
Sensors 
A simple two-dimensional line-scan camera 
system will allow co-ordinate information to be 
determined in only two axes. To resolve the third 
dimension, or depth, a further camera must be 
added. The two cameras can be arranged so that 
the field of view from each overlaps at a desired 
distance from the stereoscopic camera baseline. 
This overlapping area is termed the stereoscopic 
region, and is shown in Figure 11 for television 
type cameras and in Figures 12 and 13 for a 
line-scan stereo—cameras. If a point of interest 
lies within this region it will appear in the images 
from both cameras, however the horizontal position 
of this point will differ in each. It is this 
difference, commonly termed the disparity, that 
indicates the depth of the point in the stereo 
region. 
Line of symmetry 
   
  
Pseudo 
CONVERGENCE 
Point Stereo Region 
AFTER Movement 
  
   
   
   
   
  
[_f LINE-SCAN 
---— SENSORS W--—-— 
MOVEMENT 
AI 
Figure 12 Stereo Region for Lateral Motion 
Line-Scan Sensors 
STEREO REGION 
RFTER MOVEMENT 
   
s - stert of scen 
  
    
     
f - finish of scan 
r - right sensor 
| -. left sensor 
Figure 13 Stereo Region for Rotational Motion 
Line-Scan Sensors