International Archives of Photogrammetry and Remote Sensing. Vol. XXXII Part 7C2. UNISPACE III, Vienna 1999 
7 
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I5PR5 
UNIS PACE III- ISPRS Workshop on 
“Resource Mapping from Space” 
9:00 am -12:00 pm, 22 July 1999, VIC Room B 
Vienna, Austria 
ISPRS 
Figure 2 Number of new software packages released onto the market 1970-1996 
An important development problem in less developed countries 
(LDCs) is to increase agricultural production in order to 
generate income and employment, while simultaneously 
protecting the environment and nature conservation areas. 
LDC’s are characterised by large workforces in the agricultural 
sector (for example 63% of the African labour force works in 
agriculture, and up to 90% in some countries). A lack of 
agricultural production means that there is slow growth of 
effective demand, causing consumer buying power to remain 
weak, which dampens economic activity. Eliminating 
undernutrition is strongly connected to more rapid agricultural 
development, because the majority of the poor in less developed 
countries still depend on agriculture for food and income. 
Raising agricultural production requires the removal of resource 
constraints including adequate water supply, identifying land 
suitable for different agricultural activities, developing high 
yield plant species, or improving agricultural practices 
(fertilisation, herbicide, mechanical ground preparation etc), in 
order to increase production, and hence raise demand and 
overall economic activity. Remote sensing may contribute to 
many of these activities by providing data and derived 
information at a regional and local scale. 
In conclusion, the provision, distribution and use of information 
dominates employment and economic activity in the developed 
economies. Precision agriculture, where detailed local scale 
geographical and remote sensing information is used to more 
precisely input fertilizers, herbicides and pesticides, promises to 
cut costs and increase production in developed countires. In the 
LDCs, remote sensing and spatial information may contribute to 
more efficient agricultural production through regional 
planning, land rehabilitation, and monitoring of land use 
changes such as conversion of forest to agriculture. In the next 
section the level of operational remote sensing activities is 
explored. 
OPERATIONAL REMOTE SENSING APPLICATIONS 
Aerial photographs represent an important branch of remote 
sensing, in which visible (and near infrared) light is used to 
record conventional photographs from an aircraft. Aerial 
photographs are a mature and operational technology in fields 
as diverse as photogrammetry, forestry, agriculture, soil science, 
social sciences and geolgy. The main difference between aerial 
photography and digital imagery is that the interpretation is 
done by people, who identify objects and decide on their 
significance. With digital imagery, the enhancement, and often 
interpretation of objects, is undertaken using a computer. 
Two main techniques have emerged for mapping land 
resources. The land unit method is a holistic approach which 
identifies areas on aerial photographs or remotely sensed images 
with common properties, and assigns an attribute class to the 
area (Zonneveld 1974; Zonneveld 1988). It is a technique 
particularly suited to rapid survey in unmapped areas. In 
contrast, GIS and digital image processing of remotely sensed 
imagery is a reductionist approach, where the landscape is 
viewed as a series of separate data layer, which are combined in 
the computer to model environmental and agricultural features 
(Skidmore, 1989). The GIS approach is suited for incorporating 
quantitative models based on existing map layers, plot