. ) ..il 
441 
Sàrtryck tir Svensk Lantmdteritidskrift nr 3 1964 
Numerical Adjustment of the X-obliquity 
(X-deviation) and the Width-error (Y-devia 
tion) in the Autographs A 7 and A 8 
Pentti Kaasila, Division of Photogrammetry 
R. Inst, of Technology, Stockholm 
1. Introduction. 
The accuracy of stereo-plotting machines can be investigated by 
means of Hallert’s grid method [1 ], where 6 elements were used in 
the adjustment according to the method of least squares. The adjust 
ment of the machine is generally performed by using empirical me 
thods, which is acceptable with certain exceptions. If the adjustment 
has a direct influence upon the accuracy of the instrument, it would 
undoubtedly be better to perform it by mathematical methods. In the 
autographs A7 and A8 only the so called x-obliquity and width-error 
influence the accuracy. This report presents a numerical solution of 
these errors according to the grid method in connection with a simul 
taneous test of accuracy. 
2. The calculation procedure. 
2. 1. The autograph A7. 
The x-obliquity and the width-error have the following influence 
upon the projector coordinates in the autographs A7 (Fig. 1) and A8 
according to Lycken [2]: 
dx = 
g 
dt —■ 
g — y 
dl 
(1) 
dl 
dy — dt + 
S S 
dt — x-obliquity (x-deviation) 
dl = width-error (y-deviation) 
s — V^' 2 + (g 
y') 2 and g — 230 mm (A7), g = 240 mm (A8).