SOME PROBLEMS AND DEVELOPMENTS IN THE 
SMALL SCALE MAPPING FIELD 
T. d. Blachut 
Any summary review of such a broad field as "small-scale mapping" 
must necessarily be restricted to main topics. The task is not made easier by 
the fact that the meaning of "small-scale mapping" is different in various 
countries, and the maps are often obtained in fundamentally different ways. For 
instance, in some European countries, the maps under discussion (1:25,000 and 
smaller scales) are derived from large and intermediate scales. They are 
products of a purely cartographic process. Consequently, original mapping in 
smaller scales is restricted to occasional projects only. Also, the mapping 
conditions in these countries are unique: great density of ground control of 
excellent quality is combined with complex planimetric contents of the terrain. 
The mapped areas are close to the air bases from which the photographic airplanes 
operate. Visual or instrumental navigation is facilitated by existing maps, 
abundance of distinct land marks, and dense network of beckoning stations. 
In contrast, there are still huge territories, barely explored, which 
are difficult to approach because of their vastness and adverse climatic 
conditions. In such lands, the mapping operations are different, as well as 
the requirements set forth for the final product. 
Therefore, instead of entering a detailed discussion requiring the 
analysis of a great number of secondary factors, I propose to dwell on a few 
questions only, which are, in my opinion, of general importance. 
Growing use of computational methods 
Mapping such territories as the northern part of the American 
continent, the huge lands of South America, Africa, Australia, North and Central 
Asia, usually follows a classical pattern, well established since the last war. 
Only occasionally is a less orthodox procedure being used which incorporates 
new techniques. Examples of these are projects in Australia (intended systematic 
use of APR data), Bolivia (use of super-wide-angle photographs) and Canada 
(combination of the Aerodist technique with other electromagnetic procedures 
for determination of control, consequent introduction of super-wide-angle 
photographs and numerical methods). 
Development and use of computational methods seem to be a more general 
trend that simplifies the operations and significantly improves the quality of 
results. An indication of the general acceptance of these methods for aerial 
triangulation purposes can be supported, for instance, by the number of mapping 
centres that are using computational programs developed by the Photogrammetric 
Research Section of the N.R.C. At present, this figure is approaching the 
hundred mark. This is a most impressive number, particularly since the National 
Research Council is purely a research organization and does not make an effort 
to direct practical mapping operations. The wide use of computational pro- 
cedures proves the superiority of numerical methods, particularly in bridging 
operations, and clearly points out the direction of future development: it is 
obvious that the period of analogue bridging equipment is nearing its end. Use 
of such equipment in the operations under discussion is neither economically 
nor technically justified, and the fact that the available analogue equipment 
continues to be used for triangulation does not change this situation at all. 
The numerical approach is of particular advantage in the countries 
that do not have a large number of highly skilled technicians or prefer to use 
their trained men in a more efficient way. Persons in charge of planning and 
executing large mapping projects may like to read a study by Capt. M.E.H. Young 
[11. This publication contains extremely interesting comparative figures