436 
  
437 
meaningful data, the operator must have am absolute orien- 
tation of the model. Therefore, it has been common practice 
to provide a ^"piot sheet" which has at least two points in 
a scaled horizontal position (X and Y) and three defining the 
vertical orientation (2). ^The Coordinate values for these 
plotted points are determined from given "geodetic'" positions 
using 
  
  
INPUT OPERATION QUTPUT 
Existing geodetic Flight plan-- 
control -- Mapping ame PLANNING  «——X» Field control 
accuracy requirement requirements 
Aircraft, camera, i 
geodetic instruments "FIELD ACQUISITION emp Aerial photography 
Control, photography, 
E Contr i i 
| | measuring instruments =" TRIANGULATION e ol points in 
modei--Plot sheets 
Photography, plot sheets, 
compiiation instruments 
  
  
emp COMPILATION => Compiled maps 
  
Figure 1 
aerotriangulation techniques and the compilation sheets are 
plotted either by hand or by machine. A typical operation is 
shown igraphically iin fig. 1. 'Since' each of the operations 
shown in the figure employ separate and unique instrumentation 
and procedures, it is.a logical flow even though it involves 
à certain amount of duplicated effort. The major duplication 
is the repeated orientation of. the stereomodel. In addition, 
using these methods there is (of necessity) a great deal of 
repeated manual introduction of data leading to possible 
biunders. 
In contrast to /the analog methods, the analytical stersopiotter 
offers a completely numerical approach to the process whereby 
repetitive steps can be eliminated and the data handling can 
be structured toward a completely digital system. This con- 
cept is illustrated in figure 2. 
Field Acquisition 
Planning ut 
= Triangulation 
Cartographic — 
Output Compilation 
  
  
DATA 
BASE 
Figure 2