### Classification of Map Projection

Geography Practical

#### Index

# Introduction

Map projection is the transformation (mathematical or graphical) and representation of a spherical surface onto a plane surface. It is a means of showing the curved surface of the earth on a flat map. In other words, map projection is a systematic method of converting the curved surface of the earth into a flat map.

The nature of the Earth being three-dimensional, it cannot be fully represented on a two-dimensional surface without some distortions. Map projection aims to reduce these distortions and preserve certain properties of the Earth's surface, such as shape, area, distance or direction.

## Classification of Map Projection

There are several types of map interpolation, each designed to serve specific purposes and reduce particular types of distortion. The selection of an appropriate map projection depends on the intended use of the map and the geographic location of the area being represented.

The classification of map projections is based on various properties and characteristics of the projection.

**The main factors or bases of classification of map projection are as follows:**

## 1- Map Development Ability :

Map projections are classified on the basis of their ability to develop a map. This classification depends on the surface on which the Earth is projected. The three main types of developable surfaces are used in map projections; There are cylindrical surfaces, conical surfaces and plane surfaces. Depending on the developable surface, map projections are classified as cylindrical, conical or polar (azimuthal) projection.

## 2- Conservation of Properties :

Different map projections preserve different properties of the Earth's surface. These properties include size, area, distance and direction. Some map projections aim to accurately preserve a specific feature, while preferring to compromise on other features. Map projections are generally classified by their ability to be isomorphic (shape preserving), isosceles (area preserving), equidistant (distance preserving) or azimuthal (direction preserving).

## 3- Projection Method :

Map projections are also generally classified based on the mathematical method used to project the Earth onto a flat surface. Common projection methods include geometric, analytical or numerical methods. Each method has its own mathematical equations and algorithms for determining the change from a curved Earth surface to a flat map.

## 4- Intended Use :

Map projections are also classified on the basis of their intended use. Some projections are designed for specific purposes, such as navigation, weather mapping or thematic mapping. The choice of projections depends on the purpose of the map and the area being represented.

## 5- Flexibility or Usability :

Some map projections are flexible, allowing them to be used to display large areas with minimal distortion. These projections are known as pseudo-conical or pseudo-cylindrical projection. These types of projections provide a compatibility between size and area distortions, allowing them to be used to display large areas or entire continents.

## ------ Types of Map Projection ------

There are several types of map projection, including cylindrical, conical or polar azimuthal, pseudo-cylindrical or multiple projections. Each projection differs in terms of the surface onto which the Earth is projected and the properties it seeks to preserve.

**Some common types of map projections are described below:**

## 1- Cylindrical Projection :

In Cylindrical Projections the Earth is projected onto a cylinder which is then used to create a flat map. Often this type of projection is used for world maps or navigational charts. Examples of cylindrical projections include the Mercator Projection, Transverse Mercator Projection and Miller Cylindrical Projection.

## 2- Conical Projection :

Conical Projection projects the Earth onto a cone, which is then used to produce a flat map. This type of projection is commonly used to map mid-latitude areas. Lambert conformal conical projection and Albers equal-area conical projection are examples of conical projections.

## 2- Polar or Azimuthal Projection :

The Polar or Azimuthal Projection projects the Earth onto a particular point (the tangential plane). Often these projections are used for mapping of polar area or for mapping areas around a specific point. Lambert Azimuthal Equal-Area Projection and Stereographic Projection are examples of Azimuthal Projections.

## 3- Pseudo-Cylindrical Projection :

Pseudo-cylindrical projections attempt to balance distortion of both shape and area. Such projections are an adaptation between cylindrical and conical projections. The Sinusoidal Projection and the Mollweide Projection are examples of Pseudo-Cylindrical Projections.

## 4- Miscellaneous Projections :

There are many other specialized projections that are designed to meet specific needs. These include Robinson Projection, Winkel Triple Projection, Eckert Projection and the Goodes Homologous Projection.

## Summary :

In short, map projections are an essential tool for representing the Earth's surface on a flat map. There are different types of projections. Each projection has its own specialty and use. The determination of the best quality of map projection is based on criteria such as efficiency of map development, preservation of properties, projection method, intended use and flexibility. It is essential to understand the different types of map projections in order to create accurate and useful maps for various applications.

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Unit - I