monitored and appropriate responses planned and im
plemented. The consequences of poor management we
re demonstrated in the 1992 earthquake in Cairo where
lack of building and infrastructure control and inadequate
access routes to devastated areas meant that more
deaths ensued than might otherwise have been. Mapping
is needed for planning and development control, as a
basis for infrastructure records and as a framework for
property valuation and assessment. While not all coun
tries and communities take kindly to the idea of land and
property based taxes, an increasing number recognise
that land is a form of wealth, that taxing wealth is equit
able and that unlike other sources of income or wealth,
land cannot be hidden. A study in Indonesia found that by
having a map base for property tax assessment resulted
in a 50% increase in revenue collected.
Need for high quality water. About 1.3 billion people have access on
ly to polluted water.
While the case for urban mapping may seem to surveyors
as self-evident, the reality is that it is not. Within the Third
World there are a number of objections that need to be
overcome. The first is that in some countries the military
have dominated the mapping scene and have been more
concerned with mapping at smaller scales for strategic
purposes than at larger. The military have often opposed
the use of aerial photography on the grounds that in
formation of national security might be endangered if
photographs were available. There were extensive argu
ments with the military in Thailand, for example, before
large scale photo-maps could be produced in support of
the national land titling project; even then the photo
graphy had to be taken under the supervision of and
developed by the military. In Pakistan the World Bank had
to use SPOT imagery to assess the extent of squatter
settlement in Karachi because of the difficulties in getting
permission to obtain aerial photography. In Karachi there
are some two million squatters who have built rough and
ready shacks on government land beside an estimated
350,000 serviced private plots of land that have road
access, water and sewer supply but no buildings. 'Site
and service' plots are a major investment since they are
not subject to any land tax but have such potential that
their value is increasing significantly faster than the rate
of inflation. The upgrading of the squatter settlements,
known as Katchi Abadis, is a major problem that is com
pounded by the lack of suitable mapping.
Even where access to aerial photography is permissible,
the cost of mapping may be perceived as excessive.
The surveying profession in general has paid insufficient
attention to quantifying the benefits of mapping, and
more particularly the cost of it being unavailable. Partly
because of the military influence that saw smaller scale
mapping as essential for security and for which it was
therefore unnecessary to be concerned about price, the
true cost of mapping has often been hidden from the
public. Similarly in cadastral activities the actual costs
have not been reflected in the scales of fees. As a result
when a central or local government authority is faced with
a realistic price for mapping it often believes this to be
unacceptable. One of the strengths of photogrammetry is
that in terms of unit cost, it can provide solutions more
cheaply than by other means. It is however the gross
costs that are of concern to most administrators and since
they frequently do not know the cost of not having
mapping they are reluctant to invest in a product that can
appear to be expensive and that soon becomes out of
date.
Many countries lack cost effective methods of map revi
sion; even if the cost of initial mapping can be justified,
the cost of map maintenance and update is frequently
ignored. While it may be true that an out of date map is
better than no map at all, there has been little or no
attempt to quantify the costs and disadvantages of out of
date maps. There has also been little collusion between
the field surveyors and the photogrammetrists in how
map revision may be best undertaken, especially in a
digital era, and all too often incompatible standards and
techniques are used. There is a need for the profession
to reconcile its own technical inconsistencies as well as
to persuade its clients to invest in map maintenance.
Although map revision poses problems for small scale
mapping, it is at the large scale as used in urban areas
where the difficulties are most acute since it is there that
the pace of change is greatest. In the case of Lahore
quoted above, if it were to take six months between flying
and delivery of mapping for the city (assuming the military
agreed to this being done on a commercial contract) then
in the intervening six months an additional 75,000 people
would be living in the city.
Cadastral systems
While the rate of urban expansion and the challenges
that this poses the photogrammetrist are relatively new
problems, the general failure of photogrammetry to solve
cadastral problems is more long standing. A number of
countries have used aerial photographs as a basis for
cadastral mapping especially in the initial compilation of
registers of title. Thus in Kenya enlarged aerial photo
graphs approximately to 1 2500 scale have been used
to produce a basis from which field boundaries can be
traced while in Thailand 1 4000 and larger scale rectified
photographs have been used with the distances between
boundary markers being added by field survey to the
general outline of plots as visible on the photomaps. In
some countries, stereo-plots have been used to provide
an accurate graphical base for locating general boun
daries while in Germany and Switzerland analytical tech
niques have been used to produce numerical information
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