GENERAL CONSIDERATIONS 
  
The major factors which must be considered when 
planning a survey are: 
1l. Type and scale of the map to be produced. 
2. Availability of existing survey data. 
3. Climatic and weather conditions. 
4, Character of the terrain (topography, vegetation, 
drainage). 
5. Accessibility. 
6. The ability of the local survey department to continue 
the mapping program using the data provided under a 
mapping project. 
The above factors will determine to a large extent 
the mapping system to be employed. An effective mapping system 
should integrate advanced instrumentation and methods into one 
economic system, so that the project can be carried out efficiently 
and at a reasonable cost. But at the same time, it must produce 
data in such a form that they can be used by the local survey 
departments, which generally are not equipped with sophisticated 
data processing and electronic computation equipment. 
In tropical, inaccessible areas the most expensive 
and time consuming phase of the total mapping project is the 
collection of the necessary data in the field, prior to commencing