Definition of Map Projection and Steps in Creation Map Projection: Steps and Preserving Metric Properties (Especially for GATE-Geospatial 2022)

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Map projection is the transformation of a curved earth to a flat map. A map projection is one of many methods used to represent the 3-dimensional surface of the earth or other round body on a 2-dimensional plane in cartography. Maps cannot be created without map projections. All map projections necessarily distort the surface in some fashion.

A map projection tries to represent the 3-dimensional Earth with all its features like houses, roads, or lakes on a flat sheet of paper. This is very difficult as you can imagine, and even after hundreds of years there is no single projection that is able to represent the Earth perfectly for any area in the world. Every projection has advantages and disadvantages.

To be able to create maps as precisely as possible people have studied, modified, and produced many kinds of projections.

This Image Shows Map Projections

The world in different projections. A Mollweide Equal Area projection left, a Plate Carree Equidistant Cylindrical projection on the right.

Introduction to R

Lines of latitude and longitude, also known as parallels and meridians, form a GRATICULE or reference frame against which location can be measured. Making a map involves

  • Shrinking the real word down to scale
  • Transferring the surface detail to the map - this transfer is the process of map projection.

Steps in Creation of a Map Projection

The creation of a map projection involves three steps in which information is lost in each step:

  • Selection of a model for the shape of the earth or round body (choosing between a sphere and ellipsoid)
  • Transform geographic coordinates (longitude and latitude) to plane coordinates (easting and northings)
  • Reduce the scale (in manual cartography this step came second, in digital cartography it comes last)

The simplest map projections are literal projections, obtained by placing a light source at some definite point relative to the globe and projecting its features onto a specified surface.

Selection of a Model for the Shape of the Earth

It is further divided into following sub steps:

Diagram Shows Creation of Map Projection -Step 1

Transformation of Geographic Coordinates (Longitude and Latitude) to Cartesian (X, Y)

It is further divided into following sub-step:

Diagram Shows Creation of Map Projection - Step 2

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