494
6 c) The differences in elevation, calculated from formula (3) have
been corrected for 0,§06 difference in nadir-directions. A new
calculation has then been performed with the formulas given in
(3).
The average residual error of the elevation-measured points was
calculated to be 0.33 metres according to method 6 b. The calculation
according to method 6 c gave the value 0.05 metres.
In fig. 3 the results according to 6 a and 6 b have been compared.
Table 1.
Circle No.
Magnitude of radial distortion
according to method:
6 a
6 b
6 c
1
+ 4.1
+ 8.7
+ 4.0
2
+ 7.5
+ 9.5
+ 7.4
3
+ 9.5
+ 6.8
+ 9.4
4
+ 9.4
+ 4.2
+ 9.2
5
+ 6.5
+ 1.4
+ 6.4
6
0
0
0
7
— 10.7
— 8.5
— 11.1
8
— 26.4
— 21.5
— 24.5
9
— 47.7
— 39.1
— 47.0
Literature:
Hallert, B.: The grid method and the Y-parallax method for determination
of systematic disturbances in aerial and terrestrial photographs. —
Stockholm 1956.
Hallert, B.: The influence of radial distortion and other systematic errors
upon photogrammetric models from approximately vertical pictures. —
Stockholm 1956.
Rikets allmanna kartverks meddelande nr 27 — Stockholm 1956 (Some
Investigations Into Distortion of Survey Cameras). — Also published
separately in 1956 by L. Ekelund, Stockholm.