ginning, in the center and at the end of the strips at the disposal of the centers in 
charge. These point groups made it possible to carry out the complete calculations, 
including the adjustment, of the 3 lateral strips. They gave the control points for the 
aerotriangulation of the longitudinal strips carried out afterwards. The last-mentioned 
strips were measured and adjusted in the same way as the lateral strips. The coor 
dinates of the check points thus obtained have been considered definitive coordinates. 
For the time being no separate block adjustment has been made. 
2 — TECHNICAL DETAILS 
2.1. Preparation. 
Preparing of the prints and diapositives included the following work: 
2.1.1. Drafting of sketches. 
2.1.2. Measuring of the distances between the fiducial marks in the dia 
positives and calculation of the principal distances (the film-shrinkage has to be taken 
into account). 
2.1.3. Marking the check points in the prints and the diapositives. 
2.1.4. Selection of the tie-points between consecutive models at the optimal 
spots in the model (¡F 1 cm) and transfer of the points at the upper and lower strip 
edge as tie-points to the neighbouring strips. 
2.1.5. Transfer of the control points selected in the longitudinal strips in 
the first and last model each as well as in the middle of these strips to the lateral 
strips. 
Only natural terrain points have been selected for the points under sections 
2.1.4. and 2.1.5. and these points have been marked with a circle in the diapositives 
with the marking device of Zeiss. A uniform code has been determined for numbering. 
2.1.6. Drafting identification sketches of the items mentioned in sections 
2.1.4. and 2.1.5. 
2.1.7. Measurement of a test model with 20 known height control points 
to check possible irregularities caused by the glass bottom used in the aeroplane. 
After exact levelling the test-model (556/560) in the C8-Stereoplanigraph with 
respect to 4 control-points located symmetrically at the corners, the height-measure 
ments at the remaining 16 control-points showed a systematic spheric deformation 
of the model with a height of arc of 2 meters. This value corresponds with respect 
to sign and size quite well with the theoretical value of 2.05 meters for the earth- 
curvature of this model. So it was evident, that the glass-bottom of the plane had 
no influence on the quality of the photographs. 
2.2. Mechanical Aerotriangulation. 
All centers performed the mechanical aerotriangulation with the Stereoplanigraph 
C 8 with printing counter or Ecomat at a model scale 1:25 000. In order to guarantee 
a uniform procedure we drafted a « Zusammenstellung für die zweckmässige Ausführung 
der Aerotriangulation » (Directions for the most practical procedure of aerotriangulat 
ion) and passed them on to the other centers together with the diapositives. We 
should like to mention below the following points taken from that paper: 
2.2.1. The relative orientation is carried out according to the numerical 
procedure by eliminating the residual parallaxes up to 0.03 mm (model scale). 
2.2.2. The absolute orientation of the initial models by means of the 
control points should be done as accurately as possible.