27 
t of a se- 
nh photo- 
Lng model 
listortion, 
the pho- 
cedure of 
nt of the 
îations of 
rocedure. 
;nt. The 
1 models 
Ddel of a 
to leave 
distance 
ern edge 
th a lon- 
ientation 
ger than 
imber of 
nts were 
used for 
?ips, and 
fer. For 
pricked 
je of the 
ruments 
tted and 
3 proved 
ts often 
d in the 
iangula- 
tion without increasing the number of measurements, a different pattern of points 
for relative orientation was chosen here. As before, three points were chosen along 
the western edge of each model and three along the eastern edge. Because of the 
large longitudinal overlaps, these points do not coincide with the points chosen for 
the same purpose in the adjacent models. In addition, two points were measured 
near the principal point of each photograph. These points were used also for scale 
transfer. 
The points for scale transfer were pricked on the paper prints; the tie points 
between strips were pricked on the glass diapositives. 
Each point was pointed at stereoscopically once and its coordinates were recorded 
by means of the typewriter that is attached to the instrument. 
c) Wild Al 
According to the results of the Renfrew International Test, the Wild A7 at the 
National Research Council has proved to be slightly more accurate than the average 
Wild A7. Coordinates are recorded by means of the Wild EK3 and attached type 
writer. Before starting the measurements only the standard calibration was performed. 
The triangulation of each strip was started with the most westerly photograph 
and performed from left to right in the instrument. Compensation plates were used 
for the correction of lens distortion. 
Relative orientation was performed with to, cp, x, b Y and b z of each new photo 
graph. For this purpose, the parallaxes in six points in the usual locations were eli 
minated by means of successive corrections applied to the appropriate orientation 
elements. A correction of 4 or 5 C was given to the longitudinal tilt of the preceding 
photograph to compensate for the effects of earth curvature and systematic conver 
gence of the Wild A7. 
For scale transfer, the heights of two points near the principal point were used. 
These points were sketched, while the tie points between strips were pricked on the 
glass diapositives. 
3 — ADJUSTMENT PROCEDURES 
a) Strip transformation 
All strips were approximately leveled prior to the adjustment of the horizontal 
coordinates. At the same time, they were transformed to an approximately correct 
position in the X, Y coordinate system. This was done by means of a three-dimensional 
linear conformal transformation. 
As a result of the correction for earth curvature in the analytical triangulations 
and of the longitudinal tilt corrections given during the Wild Al triangulations, the 
triangulated strips do not have any excessive curvature in height. Therefore, no cor 
rection for such deformation prior to the adjustment of the X- and F-coordinates 
was required, and none was applied. 
The adjustment of X- and F-coordinates does not require accurate leveling 
of the strips either. 
A minimum number of ground control points was used. For the Zeiss Jena strips 
only the ground control points in the corners of the block were used. For the Nistri 
TA3 strips and the Wild Al strips the height of a ground control point at the eastern 
end of strip 5 was used in addition.