10 
in the future. All that would be necessary would be a good description of the 
boundaries and, for this, a near-vertical photograph is ideal if most of the 
boundaries are visible, i.e. when they consist of topographic features. Non- 
visible boundary points may be signalised before the photographic flight, or 
else they require a local field completion survey in which the non-visible 
points are fixed relative to photo-identifiable terrain points. 
1.5.1 Definition of Boundaries in the Terrain 
Cadastral boundaries must first be defined in the terrain. A formal 
(i.e. legal) definition of the boundaries requires discussion with, and the 
agreement of, landowners in the field and may thus be very time consuming. 
This is unavoidable, unless the English concept of "general boundaries” is 
accepted. In this connection I quote Larsson (paper 702.1, Congress of the 
FIG 1971; see also World Cartography, United Nations, Vol. XI, 1971): 
“If the general boundaries concept is accepted, this means that there is no 
need to determine the exact position of the boundary line if only the general 
course is known with adequate accuracy. In the case of a hedge or a ridge, the 
middle may be chosen without determining whether the boundary goes 
exactly in the middle or maybe even on one side. Such a concept simplifies 
the work for the following reasons. 
a It saves lengthy discussions about the exact position of the boundary. 
b It avoids much of the animosity between landowners raised by such 
discussions. 
c The exact definition of a boundary needs the presence of the landowners 
on both sides, which may be difficult and may delay the operation. Such 
attendance is not imperative if the general boundaries concept is accepted". 
Whether a formal definition of the boundaries is made, or the concept 
of general boundaries is accepted, in both cases the visible boundaries have to 
be annotated on photographs (preferably enlargements of the original 
photography), for example by a series of pricked points. Where necessary, 
complementary field survey operations have to be carried out. 
The definition of boundaries in the field may be very time consuming, 
but this is unavoidable. Not really unavoidable, however, is the execution of 
a high-precision consecutive photogrammetric restitution, although that is 
customary in Switzerland, Germany and the Netherlands.