4. Mapping Techniques of Geographical Data

Map is the simplified depiction of the geographical data about the whole earth or a part of it on a piece of plane surface or paper for better understanding of their cartographic characteristics. Maps are the basic tools for geographers and researchers for the visualization of geographic data and understanding their spatial relationships. This chapter explains the basic cartographic terminologies such as Geodesy, Geoid, Spheroid, Datum, Geographic co-ordinate system, Surveying and levelling, Traversing, Bearing, Magnetic declination, Magnetic inclination etc. in a lucid manner with suitable illustrations. It includes the detailed classification and discussion of all types of maps based on their scale and purposes (contents) of preparing the map with special emphasis on Indian Topographical Sheets. All pictorial and mathematical methods of representation of relief have been explained in detail with suitable examples and illustrations. Various types of distributional thematic maps have been analyzed with suitable examples emphasizing their suitable data structure, necessary numerical calculations, methods and principles of their construction, proper illustrations and advantages and disadvantages of their use. Step-by-step and systematic discussion of the methods of construction of maps makes them easy and quickly understandable to the readers and users. Emphasis has also been given on the detailed discussion of techniques of measurement of direction, distance and area on maps.