IV. Numerical coordination of the different model systems to one system (the
rlap of O-system).
to two : ; ;
Si and The different model systems M, Mi, M........... Mn, which all show up
adels 1 | small differences in scale and of which the directions of axis are arbitrary, must
be transformed to one system with an approximate scale and arbitrary azimuth.
Le us | This system must in its turn be fitted into the geodetic system by using the control
deter points P, and. P. :
If the system M, (called the O-system below) is chosen as unitary system the
transformation data V,, sina,, and V,, cosa,, are calculated for the systems
elagoes M, and M, according to the formulas (1).
velling ; From these data it is easy to calculate the coordinates in the O-system of the
by. the points 12 and 12” according to the formulas (2). :
racer Analogically the transformation data of the systems M, and M, (Vo: sin a,
welling and Vo. cos G4) are computed and from these the coordinates in the O-system of
nui. the connection points 23° and 23^ etc. Tung
ancy: If more than two connection points are used, the transformation is executed
Fe Care by aid of the formulas (3)—4-6)—(6x- :
es An arbitrary model in the strip may in practice be chosen as the 0-model,
xev by namely the one containing the best control quantities. The transformation com-
round. putation is executed on a special form and is quickly done with a double comput-
| ing machine (see example below).
The result of these successive transformations is that all the control points
| point and connection points are determined as to their coordinates in a unitary coor-
dinate system with an approximate scale.
stereo
points V. Definite determination of scale.
setting
under V.1. The O-system is transformed to the geodetic system and receives during this
rically operation a correct scale. The transformation data are computed by using the
ontrol coordinates of the control points (P, and P,) in the two systems. The connection
points are then transferred to the geodetic system through known transformation
ructed formulas.
'graph Of course more than two geodetic control points should in practice be used
using at the fitting in. Discrepancies may thereby arise. Thanks to the characteristics of
se the the method so small bends and variations of scale are at careful work obtained
paper. in the strip that it is possible to treat the strip as if it were only one model rigidly
>hoto- fitted into the geodetic control net according to the method for separate models
h new indicated by HALLERT in [4] pages 56-61.
per in The O-system can be given a correct scale by a number of geodetically meas-
points ured bases, the end point of which were signalled before the aerial photography.
nodels The mapping will then be executed in a separate photogrammetric coordinate
inato- system, and it is possible to make the axis directions of the latter coincide with
same | the coordinate system of the country by determining the azimuth of one or several
pe of | bases.
on in | It is evident from experiments that it is possible to determine systems of a
nodels | considerable length as to their scale by using a base of every 8th model and also
in a stereoscopic instrument of the second order (Wild A6).
