Full text: Remote sensing for resources development and environmental management (Volume 2)

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2.5 Allocation of land 
5.3 Sat 
In many developing countries, small parcels of land 
have been allocated to the previously landless people. 
While this allocation has occured because it meets 
certain political and other promises, the impact is to 
reduce the land available for commercial agriculture and 
to leave these people at or below subsistence level. It 
has also meant that large areas of land are put under 
pressure with erosion and other environmental problems 
occurring. 
3 RECORDING THE SPATIAL DIMENSION 
As stated previously control can be provided from 
existing data or it may have to be specially surveyed 
as a framework to control the multiple data. 
3,1 Position of the cadastral boundary 
There is a need to use numerical control to enable the 
position of the resources to be established. The 
cadastral boundary can provide adequate control 
especially where the land holdings are small. 
3.2 Extension of national trigonometrical control 
Where there is no numerical control provided by the 
cadastre then there will be a need to densify the 
trigonometrical network. The positioning of control at 
a spacing of better than 800 metres (National Research 
Council 1980) will be required. 
3.3 Determining control 
Where the control is not adaequate and has to be 
provided a Global Positioning System (GPS) can be used 
■for determining horizontal control to better than one 
metre accuracy. This control will be adequate for 
many purposes and may well be able to control the 
aerial photographs and satellite images especially if it 
is in the form of pre-marking or can be recognised on 
the image and used for post-marking. 
Vertical control will be required for controlling the 
aerial photographs and satellite images (especially 
SPOT) and will also be needed for resources that are 
recorded in height, water heights, water table, flood 
limits etc. 
4 THE MULTI-PURPOSE CADASTRE 
The multi-purpose cadastre will contain a variety of 
information in addition to that required for boundary 
demarcation, and will assist in the efficient 
administration of the land (Bullard 1981). The land 
parcel is the basic unit in a MPC. 
4.1 The land parcel 
The land parcel is the smallest piece of land that is 
recorded in a land register. The size of parcels vary 
from the very large, the 'latifundi' (Jacoby 1971) to 
the very small, the 'minifundi . 
Where possible, resources should be related to each 
parcel of land. With the 'minifundi' this may not be 
possible because the resolution of satellite imagery is 
not adequate; this will be achieved with aerial 
photography where the scale is suitable. 
4.2 The multi-purpose cadastre 
The MFC can be thought of as a series of planes each 
containing land related data. Figure 1 (Archer 1980) 
shows an example of the MFC depicted as 6 planes that 
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are registered by control. 
The property lines are the cadastral boundaries that 
depict the individual land parcels. The addresses or 
the property descriptions must be such that they 
provide a unique description such that there is no 
duplication within a property register and, ideally, 
within a country. 
The base map shows the improvements, houses, and the 
surface construction, streets etc. The utility lines 
show the position, three dimensionally recorded, of the 
network of services. 
Flood plains will be determined with the aid of 
vertical control. 
Land use is recorded as well as zoning which will 
relate to the legislation that is enforced to control 
activity that may be carried out on a parcel or parcels 
of land. The boundary (artificial) between the rural 
and urban zones will be of particular interest. 
Dependent on the imagery some of the above data may 
be established except for adresses. The recording of 
property boundaries will be limited to large scale 
aerial photographs or where they are depicted by tonal 
changes on airborne imagery. 
5 AERIAL PHOTOGRAPHY AND SATELLITE IMAGERY 
5.1 Aerial photography 
The limitation of the aerial photograph for determining 
rural resources is that it is in analogue format while 
much of the other data in an MPC is in digital format. 
It is possible to convert the aerial photograph into 
digital format by scanning but with a resultant loss in 
resolution. The photograph is also usually only 
available in single band format, mainly panchromatic. 
The aerial photograph is, like the other imagery, 
weather dependent. 
5.2 Airborne thematic mapper 
It is suggested that the Airborne Thematic Mapper (ATM) 
will provide data sufficient for many of the rural 
resources. An example is the Daedelus scanner which 
can provide digital data with a resolution of better 
than one metre and in eleven bands including thermal 
infra-red. Unlike the scanner carried in a satellite, 
the airborne model is flexible in that it can be 
transported to an airfield nearest to a site and await 
suitable flying conditions. Cost may, however, be a 
limiting factor in using the ATM. 
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