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9  Geodimeter point TA > 
— .] Mapping area / 
+ Photo strip C 
Fig. 22. The geodimeter polygon at the “Skellefte älv” 
for mapping to large scales. The aerial photographs were taken at] 
(600 to 1,500 metres). This method has made it possible to reduce fie 
minimum. 
The geodimeter, an instrument for measuring distances developed by Dr Bu; 
strand of the RAK Geodetic Division, has provided the photogrammetritia vi 
unprecedented means of establishing control bases for mapping of this ty 
regardless of the topographic situation. In 54 above is described the principe 
the geodimeter and some of the results obtained. 
In 1954, RAK used the geodimeter for the first time to establish control ha 
for a large mapping assignment from the Swedish State Power Board, The fiii 
work was done by RAK in cooperation with the Power Board, which also provide 
a helicopter for transportation between control points. A polygon was mex 
between two first-order control points located about 113 km. apart. Figure 2 
shows the form of the region, the location of the polygon, and the strips phot 
graphed. The photographs were taken at 4,000 metres. The distance betwèn 
the two control points, as obtained by various methods, was: 
1. Computed from given Swedish coordinates: 112,846.09 metres. 
2. Determined from the polygon measured with the geodimeter: 112843 
metres. 
3. Computed from given European coordinates: 112,848.09 metres. 
As this project was planned for experimental purposes, the coordinates ofl 
points in the polygon were also determined by ordinary geodetic methods. 
The photogrammetric triangulation has to date been completed only for fi 
southern half of the region. The following experiments have been made. Twenty 
five stereoscopic pairs in three strips have been transformed to a O-systen, ui 
this system has been scaled by means of the geodimeter base lines, 2— a 
4—5, which have lengths of about 13.7 km and 12.7 km, respectively. The fini 
scale factor is obtained as the average of the scale factors for distances 13i 
4—5. After the scaling, the scale error of — 0.09 pro mille and + 0.11 pro nil 
was obtained for the two bases. After this correction, the scale of the system v^ 
checked by computing the error for 5-B, a distance of about 45 km. An am 
OW altitude 
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