Y 
Where 
U = distance in the horizontal plane, perpendicular to the principle line 
small u = distance in the photo plane perpendicular to the principle line 
V = distance in the horizontal plane along the principal line with principle 
point as its origin 
v = distance in photo plane along the principal line with the principle point 
as its origin. 
Through proper manipulation of equations 1 and 2, an expression of scale 
change perpendicular to tne principal line can be defined by u and along 
the principle line by u^ where u is the magnification factor and is given 
by the following relationships: 
u = A (3) 
abev 
In this equation: 
In the subject equipment, the above analysis lends itself to a 
line scanning system which scans a photograph in a linear fashion perpen= 
dicular to the principal line of the photograph. The first transformation 
equation describes the conversion taking place along any selected line 
parallel to the u axis. All such lines on a tilted photograph are constant 
in scale, however, the scale of each line varies as v increases or decreases, 
In both transformation equations, the rectified coordinates are functions 
of the v coordinate, Because of this the coordinate v is considered an in- 
dependent variable. Its uriform change is accomplished by means of a unie 
form copy table motion illustrated in the lower left hand corner of Fig #20 
2 
Spread through a number or years: