ho 
Consider a rectangular block of aerial photography arranged as shown in Fig. 1. 
The runs are parallel and at equal distances apart. 
  
+5 
Run 1 ; 
  
t 
Run 2 
Do eem anum umums -——— A—-— A— — — -— D 
  
Run 3 
RE — ——— — —  —— o Ó— —À V 
  
  
  
FrG.:1 
The position of any one point in the block can be expressed in terms of the co- 
ordinate system x, y of the most southerly run, viz.: 
ris=4 
ne eg of p oq. thes To nobuameo xi 
in which & and s; are the strip co-ordinates of a point observed in run i, and d; the 
ordinate of the point where the £-axis intersects the y-axis. Now the co-ordinates 
of corresponding points observed in adjacent runs may be directly compared. 
1. The internal adjustment 
Let the observed co-ordinates x, y need the corrections Ax, Ay to give the 
adjusted values x, y. Corresponding points observed in runs 1 and 2 should show 
the same values after internal adjustment: 
  
X1 —ci X9 
or x, + Ax1 — Xa d- Ax» 
which gives Ax1 — Ax» — —(41— x2) = AXi-2 ] (2) 
Avr. 7 Ayı = —(y1 — y2) — AN io $ . * . . 
The difference between the corrections to corresponding points in runs 1 and 2 
is equal to the discrepancy between the observed values. 
For the correction of the strips the following formulae representing second 
order parabolae may be assumed to apply to the nadir points: 
ie dey ee Uus ed, ertet i3) 
Agz p. d gr. 1 
Any other point will receive the correction : 
dA 
AE = À Énadir -7 Tit. ; : (4) 
d Aé 
An = ANnadir +9 es 
© 
According to formulae (1) and (3) this may be written as: 
Ax=ax+brt+c—n(2p-<+q) | (5) 
Ay= p.a2+q.5+r+n7@a.s+b) $ 7070 5 / 
Consider now a series of tie points between runs 1 and 2 which lie on a straight 
line, so that 
  
—3 — +2 = [Inlı,2 for all points along the tie line, 
and & = & for each individual point. 
For the lower side of run 1: A512 44.2? -- (b1d- 2]|9lu2- £1) * + (a+ Ins, 
For the upper side of run 2: Ax» — as.a? -- (b3— 2lnl1,2-P2)4 + (ca— |mli,: 
2) 
N N 
Mo 
1)