A simple block diagram of the system is shown in figure 1. 
The mapping camera is a conventional photogrammetric camera which - 
provides a complete terrain coverage and consequently the basic map 
ping material for the location of the information furnished Dy the 
sampling unit. This sampling unit consists of a high resolution te 
levision camera (more than 5000 lines per mm), with a telescopic - 
lens which records a series of terrain samples onto a video-tape. 
The exposures of the sampling camera are fixed, rather than moving 
(rapid exposure slow scan mode) and provide a simple matrix in = 
which is contained the crop spatial pattern, The sampiing camera - 
covers, during each exposure, only a small area of terrain (about 1 
hectare) but the sampling frequency can be adjusted so as to satis- 
fy survey precision requirements. Figure 2 illustrates the form of 
combined output of the mapping camera and of the sampling camera. 
The sampling camera might be made up of camera clusters or be . asso 
ciated with mirror systems which permit several transects to be made 
within each mapping camera frame by the sampling camera. Figure 2 
shows a system in which three transect lines are being used. 
- SYSTEM OUTPUT 
  
The output of the system is relatively simple. The map- 
ping camera provides a mosaic or photoindex which contains the geo- 
graphical coordinates of the individual mapping camera photographs. 
Within each mapping camera photograph it is known how many sample 
scenes were received by the sampling camera. Whereas ideally, based 
upon this same information, the exact location of each sampling sce 
ne could be predicted, it is obvious that in practice the movement 
of the airplane between successive mapping shots might cause the lo 
cations of the sampling shots (on the ground) to slightly shift. 
Each sampling spot is analysed on the basis of semi-auto- 
matic or automatic pattern recognition techniques. 
  
- ANALYSIS TECHNIQUES 
  
Each sampling camera exposure presents a simple matrix of 
light levels which after passage through an analog-digital converter