1 
camera or for c = 150 mm. 
1.12. Grid measurements. 
The machine coordinates of the grid are measured according to the direc- 
tions from Commission IV:4 ISP, see fig. 2 and 3. 
1.13. Radial distortion. 
To compute the radial distortion we use the expression dz from the nor- 
mal equations for base zero for combinations of thirteen and five points, 
  
base in/out eight and four points, see fig. 2 and 3. Then we have 
  
  
wl 
(9) dr = Ÿ dz, 
where dr is the radial distortion in the grid plane, r the radius and h the 
distance between the perspective center and the projection plane. 
For base zero we get for thirteen points 
N13 
(10) dri2^ 50 
and for five points 
(11) dr. = - 
g = 
4\ 2 
where the symbols have the following definitions 
12) Nız = 3dx)92 * 46x03 * 56104 + 40X105 * 30% 106 301087 
  
  
-4dx,99- 5dxjj9- 4dx,,,- 3dx4145- 5dyj,g1- 4dyıo2- 3dY105* 
Sdy195* 44y106t °9Y107t 49Y108t 2 dy,99- 3dy,,,- 4dy,,; 
(13) Ng =. dx, +dx, +dx, -dx, -dy, -dy, +dy, +dy, 
n- 1,2,3,4,5 according to the radius. 
For base in/out eight points 
Ns 
(14) drg = 0