or multi-colours will depend, to a large extent, upon the 
  
capability of the local survey department to reproduce multi- 
colour maps and to undertake the revision of such maps. 
A map which serves as a base map for planning should 
preferably be in one colour, or in a maximum of two or three 
colours, so that other information which the planner, engineer 
or geologist wants to place on this map could be easily super- 
imposed. Another important consideration is that multi-colour 
maps are more expensive to produce and print than single colour 
maps. 
Recently, the ortho photo map has created a consider- 
able interest and some people express the opinion that the ortho 
photo map could be the answer to mapping of areas under develop- 
ment. The ortho photo map retains practically all the details 
which are contained on the aerial photograph and, consequently, 
has a number of obvious advantages over a line drawn map. However, 
the choice between these two types of maps would depend to a 
large extent upon the scale of the final map, the character of 
the terrain and upon the use one would make of these maps. 
Photo maps at a scale of 1:50,000 are not easily readable 
because many pertinent details such as roads, houses, etc. are 
Photo maps 
  
too small at that scale to be readily recognized.