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Although it might contain to à certain extent more information than a line
map, this information can hardly be extracted by an average map user,
On the other hand, photomaps as preliminary maps in the context of the
proposed system certainly serve many urgent requirements, and in any case
they are far better than no maps at all.
Furthermore, it can be stated that for certain purposes, such as their use
as base maps for resources surveys, photomaps are even preferable to line
maps, as they allow an easier and faster transfer of ihe interpretation
result from the aerial photography to the base map.
b) The execution of phase A
Especially with respect to smaller countries, with limited financia
resources for mapping purposes, it might be preferable to have the first
phase executed by either a specialized contractor or by regional production
centres, serving a number of countries and thereby facilitating the necessary
investment in equipment, human resources and skill.
If not otherwise possible, it might also be feasible to have this phase of
the work, or at least certain parts of it, executed by special technical
units to be attached to UN organisations like FAO, T.A., etc.
c) The role of technical assistance
This first phase of the total project might also be subject to technical
assistance, rendered to development countries on a bilateral or multilateral
basis. It obviously fulfils to a large extent the basic principle of technical
aid, namely to initiate with relatively small funds an as large as possible
national contribution of the receiving country.
At the same time, this type of technical assistance also facilitates a lot of
; 2 lj rati Y i
other development activities (national resources survey, integrated surveys,
etc.).
Interrelation of topographic mapping programme with resources surveys
If in the context of a development programme for a certain area, individual
resources surveys (soils, forestry, hydrology, etc.) or an integrated survey has
to be carried out, the conventional mapping systems are too slow and too expen-
sive to provide the required topographic base maps - if they do not already
exist.
As à consequence, the resources surveyors have to provide their own base maps
(uncontrolled mosaics, slotted templet layouts, etc.) to present the data
gathered in the form of maps.