9
Besides these objectives, there could be many other soughtafter
attributes like versatility, reliability and usefulness for socio-
-economic purposes.
A particular technique is considered to be better than another
only if it satisfies more closely Q, Q, C criteria.
PREDOMINANT MAPPING OBJECTIVE IN A DEVELOPING
COUNTRY IS TIME AND COST
The reduction of time required to produce a map has become the
most important objective, especially in developing countries. The
indentors (map users) are somewhat indifferent to a marginal (in
some cases substantial) cost increase if the maps could be deliver
ed to them speedily. The pressure of thè development is such that
the maps are required almost 'yesterday*. Cutting down time should,
then be the main objective that a suitable system of map production
must achieve. In order to make it possible, the time needed for
producing a map has to be examined.
CONVENTIONAL SURVEY & MAP PRODUCTION SYSTEM AND
THE PROPOSED SYSTEM
The following topographical map series are the responsibility
of the Survey of India:
(a) i;250, 000 Scale map series (1 degree x 1 degree)
There are, in all, 394 sheets covering India. They provide the
topographical base for all the maps and charts on 1:1 million, and
smaller scales, e.g., International Civil Aviation Organization
Charts for air navigation and International Map of the World. This
map series itself is compiled from 1:50,000 series. Naturally, its
sheets will be an uptodate as its component sheets. The subsequent
revision is dependent on the information supplied by local govern
ment agencies and other special purpose surveys. In any case, a
complete revision is possible only when all its 16 component
1:50,000 sheets are revised. This series, therefore, remains out
of date for most of the time. The following diagram shows the stag
es of work involved in producing this map series.
Proposed System:
A common and well known source for terrain information today is
1:50,000 photography which is generally available at intervals of
ten years or so. The 1:50,000 scale photographs can be utilised to
know the changes. The changes can be verified on the ground by
spending about 100 man days in the field and about 400 man days
on drafting in the office for one sheet. Misra (1) gives the other
details in his paper.
The satellite imagery, if easily available, can also be profitab
ly used for quick revision. Besides, for revision of small areas,
the use of Zoom-transferscope type of instruments/sketch master is
recommended.
