PRACTICAL EXPERIENCE IN DETERMINING A NET OF POINTS BY
AERO TRIANGULATION OF DIFFERENT PARALLEL STRIPS
AND THEIR COMPENSATION
by M. Zerrer, Zurich, Switzerland.
The compensation of single strips does no more offer any difficulties in
practice. We have therefore occupied ourselves intensively with the transverse
compensation of several parallel strips these last years. We have thereby
developed and tested a method which after compensation leaves no more any
contradictions, and which has the advantage of being very simple.
This method presupposes any chosen number of parallel strips connected with
each other by several transverse strips (at both ends of the parallel strips and at
least one running nearly through the middle of these strips), see Fig, 1.
By this arrangement we obtain values for adjustment of the parallel strips
from the triangulation of the transverse strips a, b and c which for reasons ot
greater exactitude are prefer-
ably triangulated forwards and
back wards.
The compensation of the
three principal (transverse)
strips is carried out by using
survey co-ordinates. Thereby
the groups of points necessary
for the parallel strips are also
obtained in survey co-ordina-
tes, Le. as a uniform system of
co-ordinates, which would not
be the case, if the compensation
c Ó c
“y p -
1
Pee
reared’. PH tds meena were carried out in strip co-
Fig. 1 ordinates.
T To obtain the data necessary
for the compensation of the whole block the following procedure is to be used:
In extending the triangulation along the parallel (filler-) strips the co-ordinates
and heights of common points in the lateral overlaps are read in the adjacent
strips. These doubly plotted common marginal points are chosen in such a way
that they follow each other in the distance of the basic lengths of the first strip,
Le. that transverse series are obtained through the transitional points of the latter,
which lie as exactly as possible in the y-direction.
After triangulation of the parallel strips every one of them is compensated
using for example the graphical interpolation method by Zarzycki. In this way
we obtain the compensated values in position and height of the common marginal
points of every strip.
The compensated values of these marginal points have, therefore, been
obtained twice, the said marginal points always appearing in two adjacent strips.
Of course we have to expect certain small differences in these values.
In the triangulation of the parallel (filler-) strips it is useful to adjust the
X- and y-register in each following strip in such a way that the readings refer to
