- 2158 - 
- Areas of very rough ground, for exemple boulder fields etc 
- Steep slopes of great extension 
A short discussion of the morphometric classification, the so called 
relative relief variation or brokenness is perhaps apropriate: 
Two areas of equal size C and D have about the same relief, as illustrated 
in fig. 1, by these represenative profiles of the terrain, but the 
frequency of braking points and the rate of change in inclination is 
greater i D than in C. We might simply say that the numbers of up-hill 
and down-hill slopes and their steepness is greater in area D althought 
the actual macro-relief is the same in both areas. The amplitude is 
about the same, but the frequency of changes is greater. Area D is said 
to be more broken than area C, its degree of brokenness is higher. 
Inversely area C can be said to be more traversible, i.e. easier to 
cross on foot or by terrain vehicle, for instance forestry machines. 
To a visistor on foot traversibility of the terrain is not simply a 
physical experience. Even small changes in the degree of brokenness 
may restrict our visual panorama. We know for instance that the 
distance to the horizon, our perception of surronding space affect 
our emotional experience of a landscape. When actually walking over 
the terrain, a more broken, more highly dissected area feels higher, 
wider and deeper than does a less broken area of the same size. The number 
of hills to cross or round, or in other words the number of landscape 
features which the eye must compass before it reaches the horizon, 
affects the perception of space as well as of time. 
A quantification of these circumstances would provide a better 
possibility of describing the subjectively experienced visual impression 
of the landscape in more objective terms and a better possibility ‘to 
make a better assessment of the suitability of any particular terrain 
for open air pursuits, recreation, sport and even the chances for 
succesful wildlife conservation of species with special ecological demands. 
A rapid mapping of the types of terrain in terms of their accesibility 
and'traversability by motorised transport directly from stereo photos 
would yeald information of great interest for forestry and other concerns 
which are dependant on ease of access to vehicles. 
Quantification of the morphometric classes has been done by statistical 
analyses of photogrammetrically recorded profiles of trial areas. The 
profiles are measured with a mapping instrument and automatically recorded 
on tape. The profile shown in fig. 2 illustrates two different 
quantification methods. Registration along the horizontal axis is 
almoust continous and can be reproduced for morphometric experiments 
at units forming multiples of 2.5 m. The profile of fig. 3 is plotted 
at different intervals. 
Due to the model in fig. 1 classification of brokenness is not possible 
by means of analysing contours of the topographical map. Althought 
the contours of the two models are much allke, there are undoubtely 
different morphometric classes. Thus, information essential to 
morphometric classification is available only in aerial photos.