element 
by the 
  
  
  
  
   
8. —- Adjusted coordinates of model points 
These points can be distinguished in * minor control points ? (whose 
eoordinates are x— b y— 4 a) and arbitrary points of the models. 
According to Roelofs’ suggestions, it is worth while to derive the 
coordinates corrections by differences with those of x-transfer points. 
The formulas for the corrections in coordinates of an arbitrary model 
point, specialized to the principal points (coordinates — b, 0) are: 
  
  
  
  
  
AX; = — Ag; + Abx; 
11 
Ay; = p ) — bAxi -,—Zz (Awi + Aw; - 1) + Aby; + ADyi > 1 
A EA DA Lu A Ab 
ZEE ———— (i — Abx; + ——— i- r— Abzi —-, 
7 pnis b 9 7 
For the minor control points : (x — b y= + a) 
AX’; = da^ — ZA; + Abx; 
a? a? DD) az 
Avi = + — An — d: hy Au - 1 F — (Api — Api = 1) + 
b b 2 b 
€ 2 — 7,2 a 7.2 € ] 
ne Aci ~ , + Go Aw; + — Abx; + — (Aby; + 
27 27 2 
a 
Abyi > i) -+ oz (Abz; Abzi — 1) 
aZ z^ 75 + b? Z 
Az’; = + ia (Ax — Ami — 1) C Ag; + - Th Agi - 1 + 7 Abx; + 
+ aÂo; - , — Abz; - , 
From this it follows : 
: AX’; ES Ax; = + ax 
a az 
Ay'; — Ayi — pex (Ax - 1774) x d (Aói - 177 Aqi) + 
2 a a 
+ 2 (Ao BR Ati) + — Abx; + — (Abz; — Abz; — 1) 
27 b 27 
az 
Az's — Azy = + ii (Axi — Axi - 1) + alAwi - ,