LT 
- (»?a)o] [(x'), mi 
(x? 2 
: (y°ı )o] [(Y a), T- ()] 
(x°01)1]* 
o — (y°01)e] [GC ) — b^) 
UT (x%1)1]? | 
) — (y°01)o] [(y”o)ı - Aj) 
-— (x°01)1] 
  
Le — (x°01)1] + (x%ı)o 
1 — (x°01)1] + (9n), 
— (x%01)1] + (x°01)o 
— (x?n)i] + (yo) 
h— (x°01)1] T (x) 
he (x°01)1] + ()*ay 
nd M: systems computed 
tion points O1” and 0!” 
he Mo and My systems 
he connection points 0 
inates of the connection 
y etc. 
las 
n the models imespetir 
Even if the common put 
| can be obtained. 
se and connection poils 
| model. 
s into a common sysiel 
n computations, The scale 
d in the field (se fij. 1 
  
6) When inserting the negative or the diapositive in the stereo-plotter alternate 
re rotated 200^, thus eliminating certain systematic instrument errors. 
RO the models are connected numerically, triangulation is possible not 
m i but models belonging to various strips can be combined. In the 
adt connection is made by distinct image details. 
ns > in triangulation each model is levelled with the aid of height control 
" orientation need not be repeated when the model is to be plotted, but 
ife data except the base (bx) can be set directly on the scales of the 
Jotter. 60 to 70 per cent of the time used for triangulation in the stereo-plotter 
is thus recovered during plotting. i | 
Attempts were made in 1953 to combine the different models mechanically 
(t. (24). 
553 Grid triangulations 
If an accurate planimetric control net is to be successfully built up by means 
of photogrammetry on the basis of sparse, isolated geodetic measurements (bases 
or polygons), both the errors of the starting material (= photographs) must be 
known and corrected as accurately as possible at the plotting stage, and the 
measurement in the stereo-plotter arranged so as to avoid unfavourable propaga- 
tion of the inevitable constant errors of the instrument in the strip for triangulation. 
With regard to the first item, attempts have been made at RAK to determine 
enpirically the total radial distortion of the aerial photograph (see 52 above) 
ind to correct it with correction plates in the stereo-plotter. The effect on tri- 
mgulation of the systematic instrument errors, which particularly in old types 
of stereo-plotters and in instruments of the 2nd order may be considerable, are 
ssentially reduced both by carrying out the measurement only in one basic 
psition of the instrument and by rotating alternate stereoscopic models in the 
strip 200°, 
The effect of rotating the model has been studied by grid triangulations in 
the Wild A5 and A6 stereo-plotter. These tests were intended to examine how 
4constant planimetric deformation of the grid model caused by instrument errors 
is propagated in a strip with ten models both without (Alt. I) and with rotation 
(Alt, IT) of alternate models. 
031 Grid triangulations in autograph A) (test year 1953) 
The following data apply for the triangulation. 
Grid: Wild 18 x 18 em 
Projector constant: ¢ — 100 mm 
Base in grid: 60 mm 
Distance of connection points from the image centre (in grid): 60 mm 
Lin the instrument: 400 mm 
Number of control points: 2 (00° and 910°) 
Number of models: 10. 
  
  
re ie 
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