VII. Summary of the principles of the method and the most important advantages.
The following three moments are essential in the construction of the method.
A. The orientation of the stereomodels is performed with the base set in the
same position (e.g. “base inwards”) and every other model is turned 200° in rela-
tion to the other models, when placing the photographs in the plotting instru-
ment. Thanks to this the effect of the systematic instrument errors is compensated.
B. Connection points are drawn on the negatives. Therefore the scale and azi-
muth can be accurately transferred between the models independent of the cha-
racter of the terrain surface (monocular setting of the measuring mark).
C. The models are connected numerically and therefore the application is not
limited to triangulation in strips.
The following advantages can be mentioned:
1. Plotting instrument of second order can successfully be used for triangulation
(e.g. Wild A6, Kelsh Plotter).
2. Separate coordinate systems of considerable length can be built up through
O-systems which are determined as to their scale by means of geodetic bases.
These can be laid out in such terrain in which the distance measuring can easily
and accurately be performed.
3. Triangulation can also be performed perpendicularly to the flight direction.
From this it follows that a photogrammetric control net can be built up with
arbitrary shape (e.g. L, T, E or H-shape). The planning of an aerial photography
can therefore be made independently of the localization of the control points.
4. Thanks to the cross-points the stereo models can be graphically fitted into
the map very accurately at the plotting.
5. When the pairs of pictures are orientated again in connection with the plott-
ing, the orientation work is reduced essentially since the tilts and the base com-
ponents are known.
References:
[1] Blachut, T.: Aérotriangulation au stéréorestituteur Wild A6, Fotogramme-
triska kongressen i Haag 1948.
[2] Ekelund, L.: Modelltriangulering — En ny metod fôr fotogrammetrisk stom-
mätning, Fotogrammetriska Meddelanden, Institutionen fór fotogram-
metri, Kungl. Tekniska Hógskolan, Stockholm 1950.
[3] Fagerholm, P. O.: A study of mechanical radial triangulation and some
related problems in modern mapping, Stockholm 1952.
[4] Hallert, B.: Ueber die Herstellung Photogrammetrischer Pline, Stockholm
1944.
[5] Hallert, B.: Contribution to theory of errors for double point intersection in
space, Kungl. Tekniska Hogskolans handlingar, Stockholm 1950.
[6] Lófstróm, K. G.: Latest Development in the Direct Determination of the
Outer Orientation in Finland, Haag 1948.
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