This characteristic has limited the usefulness of the 
1:50,000 series for estimating areal extents of these 
features. The point symbols used are supposed to be 
placed within a polygon and depicted as area symbols 
(see figure 3). 
  
  
  
  
  
   
  
  
  
  
  
Light Forest . tt M dp ME T I EU 
aims rales inet ALI nen AE ee T Eu T 
Cultivation i : s: Y eso edid ne CR s eu [ERMEES 
Áreas liable to flood i. ma er A Lots = 
Savannah Woodland ....... in MES MT ^ LM 
“Parkland Savannah . “ = A E 
7 Figure 3: Vegetation Classes decer as area symbols 
This problem of inappropriate delineation of area feature 
boundaries is resolved in the 1:25,000 map series. 
4.1.2 . Unit of measurement: Except for north western 
Nigeria, the unit of measurement on the 1:50,000 series 
are based on the imperial system of measurement. Values 
for benchmarks, spot heights and contours are shown in 
foot with the contour lines having a vertical interval of 50 
feet. This problem would necessitate conversion from 
foot (imperial) to metre (metric). 
4.1.3 Boundary Demarcation: On the 1:50,000 map 
series only the provincial boundaries are shown and the 
regional, provincial and divisional headquarters have 
their names underlined. These administrative units are no 
longer relevant to the present day, where the federal, state 
and local government area (LGA) dichotomies are in 
place. The evolution of the boundaries of the present 
thirty-six (36) states and LGAs has really been complex 
(see Akinyemi, 1997). 
4.1.4 Projection: Information provided as regards 
the Universal Transverse Mercator (UTM) projection was 
generalized as “Grid: Nigerian Colony West Belt”. The 
Latitude of Origin is stipulated as 4° 00' East of 
Greenwich and the Meridian of Origin as 4° 30' does not 
coincide with the West Belt of the Nigerian UTM zone 
Comparatively, the marginal information produced on the 
1:25,000 series shows UTM Zone 31, the Meridian of 
Origin of 300! East of Greenwich, the Latitude of Origin 
of 0°00" North of the Equator. 
4.2 Problems associated with mapping in Nigeria 
Until the Federal Surveys digitalisation effort, digital 
mapping was done haphazardly without any form of 
coordination and this led to duplication of effort which 
was really wasteful. Existing maps of all types were 
digitised by private individuals and organisations to be 
used in a GIS environment. 
4.2.1 The obsolescence of existing paper maps 
The degree of obsolescence of the several topographic 
map series vary with that of the 1:50,000 spanning about 
36 years (see table 1). Since these maps are the base 
maps for the production of thematic maps, their 
obsolescence is a major handicap to mapping in Nigeria. 
This has led to individual states or private companies 
(such as Oil exploration companies) having to revise 
topographic maps of their area of interest. A case in 
mind is the map revision of Southern Nigeria by Shell 
Petroleum/Nigerian National Petroleum Company in 
1990 and EPI's revision of the same maps between 
1991 — 1995. There is bound to be such duplication of 
effort in revising the same map, resulting in disjointed 
spatial databases in several organisations. This amounts 
to a waste of scarce resources and data integrity problem 
would ensue. The United Nations (UN) has subsequently 
recognised that except for Kenya and Zimbabwe, most 
African countries have not maintained their geodetic 
network, base-map stock and mapping capacity 
(Bujakiewicz, 2000). 
4.2.2 Persistent use of analogue mapping 
equipment: The Nigerian map-making environment as in 
most African countries, is still dominated by the 
laborious, expensive and time consuming conventional 
photogrammetric and cartographic techniques. The use 
of these old fashion analogous instruments and methods 
cannot satisfy the requirements for digital information 
which is requested from photogrammetry/remote sensing. 
Graphical or computer supported stereo plotters and 
analytical plotters based on optical photography are too 
slow and expensive for production and revision of 
medium and small scale topographic maps, as well as the 
creation of topographic digital databases. This situation 
would make it impossible to use digital satellite imagery, 
which would be cheaper for revision of topographic 
databases and digital maps than aerial photography 
(Bujakiewicz, 2000). There are only a few countries in 
the African continent where the digital photogrammetric 
technologies have been implemented in the last few 
years, such as South Africa (Clarke, 1997 cited in 
Bujakiewicz, 2000). 
4.2.3 Inadequate funding of mapping projects: 
The 1:50,000 map series were produced with the 
assistance of the Government of Canada under the 
Special Commonwealth Africa Aid Programme. The 
government’s (Federal, State and LGA) policy and 
emphasis on quick-yielding ventures have adversely 
affected the funding of mapping projects since gaining 
independence from the British in 1960. They seem to 
evaluate the benefits of maps from the standpoint of 
tangible returns and revenues. They have for long failed 
to see the usefulness of maps as input for meaningful 
planning and the base for sustainable development. 
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