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—————7 Terrestrial measurement 
Photogrammetric mapping Without signallzing Tord 
Scale 
0 /00 m 
N de 
Fig. 1. Result of two different mappings of a brook between dense trees. 
In conifer districts, however, with high and dense 
forest, signals usually have to be placed in treetops 
or on long stakes to make them visible in the photo- 
graphs. 
The combination of high and dense forest and 
natural boundaries gives difficult cases. A not unusual 
example is shown in Fig. 1, where the boundary fol- 
lows a brook between dense desiduous trees. The lines 
represent accurate terrestrial measurement and photo- 
grammetric mapping according to method b) above, 
namely without signalizing. 
A preposterous fact in this work is that at the 
places where the effort and expence to put up a good 
signal is great, and thereby the temptation to omit 
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7 
it or making it too simple also is great, the necessity 
af having a visible signal usually is at maximum. The 
reason is that recording points without signal at such 
places probably will involve great errors, also com- - 
pared with other points without signal. 
The influence on the value of the standard error, 
of a relatively few great errors caused by reasons 
explained above, may be strong enough to hide the 
high accuracy of the majority of the points, where 
the signals are visible. This will lead to the impres- 
sion that most of the efforts in signalizing is wasted. 
To be able to take the consequence of this and 
perhaps completely omit signalizing, an investigation 
in the method b) above was decided to be carried out. 
PLAN FOR THE INVESTIGATIONS 
The main test area chosen is named Idd and lies in 
the sout-eastern corner of the country. The height 
above sea level is between 0 and 230 m within the 
100 km? large testfield. A mixture of types of topo- 
graphy and vegetation is found, typical for large parts 
of the south-eastern Norway. There are flat cultivated 
areas, both steep and flat forests with varying types 
of trees and densities. Also the estates and their 
boundaries are representative for greater parts of the 
country. 
The aim of the investigations is mentioned under 
the description of method b). The working plan is: 
Mapping in scale 1: 5000 about 1000 boundary 
points from four different series of photography, 
without having signalized the points. The four series 
are: 
Scale 1 : 20000, camera wideangle 
15cm 23 X 23 cm 
Scale 1: 15 000, camera wideangle 
15-cm 23-:X.23 €m 
Scale 1: 10000, camera wideangle 
1S em 23 X 23 eom 
Scale 1: 15 000, camera normalangle 
21 cm 18 X 18 cm. 
After signalizing the same points and making a new 
photography in scale 1 : 15 000, the plot from this 
one will be used as control for the first ones. 
In addition to this main program some supple- 
mentary works have to be done: To find the ac- 
curacy of the controlpoints, comparing different 
field operators, recording the time consumption, 
evaluating the methods etc. 
Fundamentally the plan is followed, but mainly 
owing to the bad weather conditions the summer 
1960, the photography became a bit more complicated. 
When nothing else is mentioned, the following in-