Appendix £2 
FROVISIONAL SPACE COORDINATES (New Version) 
(Method of weighted means) 
1, If photo plane is parallel to ground plane, then 
  
  
  
  
  
  
X =(yo-Y3 X + X3-xoy+a); Xe (y3-yAX€X4-X5 7X3 «b )Xo* (Y1-yox4X5734y«0)X5 
a+b+c 
Y =(y2-y3 X + X3-Xoy+a TT Y*c)Y3 
; L0&+ b+6 
2 +H Yo~Y3 X + X3-X5 +a)Z4 € (Y3-yqx1-x Xi-X3y«b)Z2« (YT- 24382734 y4c)25 
a+b+c 
gives coordinates (X,YZ) of general pt P in the gronnd plane 
if its photo coords are (x,y), the ground plane being 
defined as the plane P,PoP7 throngh the three knovm pts, 
a = X2Y3 - *3yo 
where:- b = X3Y4 - X4Y3 
e zm NS 7 XN 
and, in particular 
M 
U z 8X4 * bX5 4 cX; 
a+b+ C 
V = BY, + bY, 4 cY; 
a+ b 4e 
W = aZ4 + bZo + cz i. ; : ; 
—— + M where H is estimated 
a+b+c flying height above 
ground plane, 
Ze fais) fromthe above, approximate coords (U ,V,W) of the air 
station, use the three chserve ation equations based on the ground 
tri angle P,PaF 3 to get accurate coords, 
3. With these accurate coords, replace: 
  
  
  
(x, Yo X ) by Xi * AU, Y. AS, Z, + AV) 
EI 1*3 144 | 
vhere ® i=f | (0- x ^. (y - 0 + (Wo 7 2 
E 2 > — —# 
Xi‘ "+Yj j°+ $° . 
(1 = 1to3) 
so as to produce a new ground plane vhich is parallel to the 
photo plane. 
4. The equations in para 1 are now exact, and all provisional coordinates 
in the ground plane maybecomputed. 
De To obtain final provisional coords for a pt cormon to two photos, 
these are 
oN, Ye, Z4 
14A 14+ A 14^ 
and one solves for Abetween the three equations implied by this 
identity, (being careful to avoid the spurious solution =M= = 1). 
  
d ir 
=i dure, Ya, ‘dug 
1/4. 14A. 14M