9. HALLERT, B.: Determination of the Flatness of a Surface in Comparison with a Control Plane. The Photo- 
grammetric Record. 1960, April. 
10. — Über die Herstellung photogrammetrischer Pläne. Diss. Stockholm 1944. 
11. HArry, H.: Die kontrollierten Versuchsmessungen Oberriet der Internationalen Gesellschaft für Photo- 
grammetrie. Les essais controlés Oberriet de la Société Internationale de Photogrammetrie. Photogram- 
ria 1957—1958, No. 4. 
12. MôLLER, S. G.: Metod att bestümma hójdskillnader i terrángen med hjálp av parallaxer mitta 1 flygbilder. 
Svensk Lantmäteritidskrift 1957, No. 3. 
The references 2 to 5 are also to be found in Int. Archives of Photogrammetry, Vol. XII, 1956. 
COMPARISONS BETWEEN THE RESULTS FROM 
SUB-COMMISSIONS IV:1 AND IV:4 
At the end of March 1960 the results of the investigations of Sub-commission IV:1 were made 
known. The mean square values of the discrepancies in planimetry and elevation check points of 
the models of Monti di Revóira from the cameras RC7a 10/15 em, plates, and RC5a 11.5/18 em, film, 
are of particular interest, since they can be directly compared with the predictions under point 3.4 
above, which were made with respect to the residual y-parallaxes only. 
In Table 8 below, the results from the two Sub-commissions IV:1 and IV:4 are compared. 
  
  
  
  
  
  
  
  
Mean square values of the 
discrepancies on the ground in mm Diff. mm 
‘amera ete. ’oordinates 7 7 
pug sonate According to | According to IV: —1V:4 
[V:4 | IV:1 
RC5a 11.5/18 æ 100 114 14 
Film y 100 186 86 
2 133 256 123 
RC7a 10/15 x 120 96 — 24 
Plates y 120 121 1 | 
2 160 194 34 | 
  
For the evaluation of the results the following should be noted: 
1. According to Sub-commission IV:1, about 5 per cent of all coordinate discrepancies have been 
found to be caused by “gross errors” and have therefore been omitted by Sub-commission IV:1 from 
the computation of the mean square values. The definition of such “gross errors” was, however, 
made with respect to the magnitude of the errors only. Consequently it seems very probable that 
there are more discrepancies of the same type (“gross errors” or mistakes due to the geodetic measure- 
ments, incorrect identification etc.) and of “acceptable” magnitude according to Sub-commission 
IV:1 which have been included in the mean square values and which may have an increasing effect 
upon these values. However, the y-parallaxes will not be influenced by such errors. 
2. Fundamental operation No. 1 (the photography) has not been checked under real working 
conditions. There may therefore be systematic errors in this operation which do not influence the 
y-parallaxes (e.g. curved locating back in the film magazine). In any case uncorrected influence of 
earth’s curvature and the atmospheric refraction will have systematic effects upon the model coordi- 
nates, causing discrepancies in the conditions of the check points, in particular in elevation. The 
y-parallaxes will not be influenced in a corresponding degree, owing to the correlation. Consequently, 
the systematic sources of errors mentioned have certainly contributed to the larger mean square 
values of the coordinate and in particular elevation discrepancies according to Sub-commission 1V:1. 
3. The largest differences are found for the y- and z-coordinates of the models from the camera 
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