thus coordinates work that otherwise consists of a series of random and in 
adequate field investigations. 
Once the soil and rock materials, groundwater conditions, and geological 
features have been identified on the vertical aerial photographs, it only remains 
to complete their interpretation by translation in terms of engineering problems. 
While aerial photo interpretation is applicable to some extent in practically all 
phases of engineering planning, the greatest benefits can be realized if aerial 
photo interpretation is employed at the outset, when the site for the project is 
being selected. The relationship of the site location to the ultimate success of 
the project, plus the ease with which favourable site locations can be distin 
guished from the less desirable locations on vertical photographs, permits this 
approach to fulfil the requirements of modern engineering planning at a 
lower cost. 
Site locations having favourable foundation conditions and a natural supply 
of suitable construction materials lead to economical designs, lowered con 
struction costs, and assured success of the project. The ability to evaluate these 
problems by aerial photo interpretation, assisted by a limited amount of field 
work, obviates a number of difficulties that are very often encountered when 
conventional field methods alone are employed in making site selections. 
The most efficient approach to the overall economic development of new or 
extensively cultivated lands is by way of an integrated survey of the natural 
resources using aerial photo interpretation as a starting point. The region then 
is analysed simultaneously by a team of experts, such as geologists, geomor 
phologists, soil scientists, foresters, botanists, etc. and thus all aspects of the 
physical setting are studied and mapped. This method has become more pop 
ular in recent years and will certainly be of ever increasing importance in the 
future, since it is the only practical way by which the solution to the problem of 
rapid large scale economic development can be achieved. The method is, 
amongst others, applied by the C.S.I.R.O. in Australia, the Air Survey Branch 
in Ceylon, the Geographical Survey Institute of Japan, etc. 
The starting point for the investigations is usually the present utilization of 
the various landform units of the region. The necessary data for this land use 
map - on which the vegetation often is also indicated - can be easily derived 
from aerial photographs in combination with a field check. Land use mapping 
from the air is therefore certainly one of the most promising subjects of geo 
graphical photo interpretation. 
The second phase of the work will be the detailed analysis of the terrain in 
all its aspects, such as landforms, water features, soils, geology, etc. A separate 
map will be made for every aspect studied. These maps will give an insight 
into the potentialities of every part of the area and they will therefore be a 
guide for the planning of the most efficient future land use. The regional planner 
will find in this map series the essential information for his development 
scheme. 
The regional complex and its interrelationships cannot be studied com