-04 Z -200 "Qe -29 Q4^ 15 0 x5 = 
706 o MJ, +03 "44 Üüsk 0 20 
+5 
-Q£ 49 -53 +63 +00 02 
-03 -25 -23o +95 m Qs ht LS 
+/0 
Qo: -£4 3 "s +33 Qo 0. 0 02 
00 -37 455 bdo +49 0012 “ 0 
HS 
+Q2 +O) rie 22 76,6 +02 N À x 
+04 +02 *27 227 "95 04 +20 A 
+25 hy 0 
+05 +29 +02 +62 Qo 05 
"D +5 
“07 +42 +04 +394 #50 i) +25 +20 +/5 
Figure 6. 
Errors in height differences of 20 resp. 30 m, ® and e — 39, x — Qf. 
The effect of the tilt of the left picture is shown by the left figure. The 
effect of the tilt of the right picture is shown by the middle figure. 
The diagram shows the summed up errors for 4 h = 20 m. Flying altitude 
= 4 000 m. Focal length — 0.15 m. + - 
Table 5 + 
Errors in height differences of 20 resp. 30 m for different flying altitudes 
and for @ and ® = 3°, Focal length = 0.15 m. 
  
  
Difference Flying altitude 
In; height 2 000 m 4 000 m 6 000 m 
20 — 20.2 dm 20.0 dm 19.9 dm 
30 305 >» | 301 » — 30.0 » 
the error of a height difference, located in the upper right corner 
of the left picture, is obtained according to table 5. 
To give an idea of the errors, which can normally be expected, 
a calculation has been performed by using the average values 
of o and o presented in a thesis by Dr P. O. Fagerholm. 
These average values, however, are derived from pictures of 
relatively low flying altitude, for which according to the same 
12 
-