cadastral parcel. For the determination of the surfaces, obviously some 
form of geometrical survey is needed. It is clear, however, that this survey 
need not be very precise. Firstly, the land tax to be paid is only a fraction 
: of the product of parcel surface and land value; secondly the latter value 
—being an estimate only— of necessity cannot be very precise. For the legal 
protection of rights to landed properties, these rights must be registered in 
a legal cadastre, and the parcel boundaries defined by relating the positions 
of the boundary points to a number of "permanent" reference points, by 
means of a geometrical survey, in such a way that they are reconstructable 
at any time. 
1.3 The Advantages of the Conventional Use of Photogrammetry 
In the past twenty years photogrammetry has been used intensively 
in cadastral surveys in such industrialised countries as, for instance, Switzer- 
land, Germany and the Netherlands. In the former two countries, the 
cadastral boundaries are usually “artificial”, i.e. the boundary corners are 
monumented and the boundaries are the straight lines connecting these 
monuments. In the Netherlands, cadastral boundaries are usually “physical”, 
i.e. they are formed by topographic objects such as walls, fences, hedges 
and ditches. In Switzerland and Germany numerical stereo-restitution is 
applied usually (i.e. the model co-ordinates X, Y, Z of the—signalised— 
cadastral monuments are observed in a precision plotter and subsequently 
transformed into terrain co-ordinates), while in the Netherlands it is usually 
large-scale graphical stereo-restitution (normally at 1:2,000) which is carried 
out. The experience obtained from these methods in these countries has 
shown that the application of photogrammetry, as compared with modern 
field survey techniques, is particularly advantageous—timewise and costwise— 
in the following two cases: 
a where many of the cadastral boundaries are formed by air-visible topo- 
graphic features such as walls, fences, hedges and ditches, and/or 
b where, in addition to cadastral boundaries, other topographic features 
have to be mapped; in other words when the mapping is for a multiple 
purpose. 
The economic advantages of such high-precision photogrammetry over 
a field survey may be significant (cost reductions of 20—50% have been