- = 
If a given photo has p photo Pts R,Rj.... Rs oamena 
station O, principal pt P, then tfie nece sary 
2p-1 observation equations should be obtained from 
the 2p-1 Space angles RIP, R,OR,, R50P, R50R;... 
eO RSLUOP, R19 Rp: R, P. 
Rejections at this stage are clearly very convenient, for, 
if one wishes to eliminate the pt R., one merely omits 
the three observation quations baseä on Space angles 
R; 40R; > R,0P, R,OR, and replaces them by a single 
observät ion e ti A Re. 
S quatio ased on space angle Rs OR; 41 - 
The tilt components of a photograph, if required, may be 
easily obtained: the fore-and-aft and lateral tilts 
from the direction cosines, in space, of the line 
through the principal pt; the swing from a further 
"dummy" photo pt, at the end of the X axis on the photo 
plane, This pt need not be included in the main 
adjustment, but may be obtained by a separate similar 
computation. 
Special cases:- 
a) For a 3 x 3 stereoblock, rigidly based on 6 height pts 
and 3 ground control pts 
12 photo pts ) 
9 camera stations 
9 principal pts 
leading to normal equations in 69 variables based 
on 75 observation equations; 
b) For a 3 x 3 block, flexibly based on 6 height pts 
and 3 ground control pts 
9 camera stations 
12 photo pts | 
9 principal pts 
leading to normals in 81 variables based on 87 observation 
equations. 
c) For ali x 2 block, rigidly based on l height pts and 
5 ground control pts 
12 photo pts 
8 camera stations 
8 principal pts 
leading to normals in 66 variables based on 72 
observation equations,