With the notation introduced above we may consequently write; 
X = à (O,x) E (1) 
Formula (1) expresses the general problem of photogrammetry, indicating a 
functional relation between the model X  , the plate coordinates X and 
the orientation parameters O . Introducing the plate measurements, their 
residuals and the residuals of the given control data, we obtain, with respect 
to (1), a system of observational equations of the form; | | 
£ (v,V) = F(0,X, £) (2) 
The roots of the corresponding normal equation system represent the numerical 
Solution of the general photogrammetric problem. The result, as expressed by 
" formula (1), has been explained as an integrated effect of the contribution 
of all the individual rays. Because no one ray distinguishes itself basically 
from any other ray, this interpretation suggests that for an individual ray, 
& corresponding functional relation exists which is obtained by simply 
indexing the corresponding parameters, thus, leading, according to formula 
(2), to the corresponding observational equations: 
Fv Vi ) = F (Oi, Xj, Aij) (5) 
To comprehend this result we recollect that the bundle of rays of an idealized 
physical photogrammetric camera has its geometrical representation in the 
concept of the central perspective. Any photogrammetric bundle can thus be 
considered as a population, the members of which are the individual rays. Any 
algebraic expression representing a single ray of such a bundle, may thus be 
envisaged as representing, collectively, the bundle in its entirety, by simply 
omitting the index denoting the specific ray. 
Because any one photogrammetric bundle is based on the concept of the 
central perspective, and any one photogrammetric problem may be considered as 
a combination of any number of such bundles, it follows that an equation 
representing the geometrical properties of an individual ray can be considered 
as adequate to express, collectively, the problem of analytical photogrammetry. 
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