of all passpoints were to be measured, and noted on a special form and sent to Stockholm,
Stereoinstruments of the first and second order, as well as stereocomparators could be used, Relative and abso-
lute orientation could be performed according to the method usually used by the participant,
The influence of the curvature of earth should be compensated for by inserting ii (0.01 centigrade) y -tilt per
km base length to the second projector. That corresponds to adding (with correct sign) 16 cm to the x-coordi -
nate of point 5 of the first model per km base length and km flying height.
The orientation of model 2 to model 1 in the Wild A8-type of instruments could be done in the following way.
;
e i
gi
Ç i 2
a. Insert the photographs 1 and 2 (Figure 5.1) in the picture carriers and perform the relative orientation. Orient
absolutely on the 5 given pass-points (7-11). Measure the machine -coordinates of the pass-points and the com -
parison points of model 1/2 and note them,
b. Measure the x-y -z- coordinates of the right projection-center (5 in the figure) in the following way.
Set the z-carriage in a low horizontal plane and read the x-y -z -coordinates of the pass-points 8, 9 and 11(also
7 and 10 if desired). Set the z- carriage in a high horizontal plane and read the x-y -z- coordinates of the same
pass -points.
Calculate the z-coordinate of the projection center with the aid of the set of similar triangles, which are defined
by the measured x-y -z-coordinates of the pass-points and of the nadir of 5. Calculate then the x-y -coordinates of
the projection center, using the mean of the z-coordinates and the same set of similar triangles.
c. Move the photograph 2 to the left picture-carrier and insert the photograph 3 in the right picture-carrier. Per-
form the relative orientation of model 2/3.
d. Measure the machine -coordinates of the pass-points and the comparison points of model 2/3 and note them.
Measure the machine-coordinates x, y, z of the left projection center (5 in the figure) in the same way as in e
section b.
2/3 to model
. . . . . » ray
e. Transfer by means of three -dimensional coordinate transformation the machine coordinates (x, y, z) of model
1/2, using the common points 5, 8 and 11. Enclosed you will find a program in algol for that transformation
(Appendix 5.1).
expressed
When transforming the coordinates, each of x, y and z must be/inthe same units, The curvature of earth should
be observed.
The program for the coordinate transformation is performed according to the paper by Professor E,H, Thompson
in Photogrammetria XV, nr 4, 1958-59, p. 163-178.
B. Sc, C, -U, Thorsell wrote the program,
