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REMOTE SENSING ACTIVITIES IN AFRICA 
By 
OQlu 'Funso Olujohungbe 
Chief, Cartography and Remote Sensing Unit, United Nations 
Economic Commission for Africa 
INTRODUCTION 
The earth isa finite planet with limited resources. As population continues to grow (particu- 
larly in Africa with growth rate approximately 3 per cent per annum) makingan ever increasing de 
mand on these resources, their wise and prudent management becomes a matter of necessity. 
Such management, undoubtedly, will depend upon better knowledge of these resources — iderr 
tification, measurement and inventory, the results of which are needed by the resource planners. 
Remote sensing, as a technology, has offered great potential in producing a widely consistent 
data base which resource planners have found most useful as an added-value tool for natural 
resources development. When used in conjunction with cartography, we see changes in our perce- 
ptions, methods of data analysis (better enhanced) yielding a wealth of reliable information for 
planning and decision making for rational and judicious development of resources. 
Remote sensing, a term first coined by geographers of the office of Naval Research in the 
United States in early 1960s, was then simply defined as "the acquisition of information, about 
an object without physical contact.” Whilst this is still basic to its later definition, the term is 
now universaily used to cover pre-occupations involving gathering and processing of information 
about the surface of the earth, more especially its natural and cultural resources, through the use 
of photographs and similar data acquired from an aircraft or spacecraft (satellite). 
Before concluding this introduction, let me recall a few things about the development of the 
technique. There are two distinct or discernible epochs in the development of remote sensing, 
namely, the period before 1960 and the other, from 1960 up till the present time. 
During the first period, that is, before the advent of the photographic camera and the airplane, 
resource information was generally acquired by direct observation on the ground. Not satisfied 
with this time cansuming and uneconomical mede of data collection, resource planners resorted 
to the use of balloons, a device which provided more aerial cover. As scientific endeavours knows 
no terminal point in investigations, the developed countries of the world, notably the United 
States, England, France, Germany and Russia, continued to improve the sensor systems — optical 
glasses were deveioped for lenses and the design of camera systems incorporated the improved 
lens designs. Today, experiments are still being conducted with a view to developing cameras 
and lenses (sensors) which will be free of defects that vitiate the quality of the aerial photographs 
and/or imageries. The development of infrared and radar devices found useful applications 
during the Second World War; the development of infrared sensing devices (detectors) at this 
period, with proven satisfactory results, opened the way for the development of modern air- 
borne optical mechanical scanners, radiometers and spectrometers. 
it is also noteworthy that with the advances in the design of cameras and lenses in the early 
thirties, coupled with the increasing reliability of aircraft as a more stable platform than balloons 
medium — and low-altitude aircrafts became the primary means of collecting geographic resource 
information. As a result of further experimentation and research after the Second World War, 
remote sensing from spacecraft became the standard mode of data and geographic information 
acquisition.