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Coordinate System

Coordinate System

Introduction

Initially, when talking about the coordinates, it is a set of numbers. Through these numbers, the location of any landmark or geographical phenomenon on the surface of the globe is identified, for example, when knowing the coordinates of the location of a two-dimensional (X,Y) house, we can reach this house, and if The height of this house above sea level is known, so the coordinates (X,Y,Z) can be represented in three dimensions.

There are two types of coordinate systems:

1. Geographical Coordinate Systems:

The locations of landmarks and phenomena on the surface of the Earth are identified through lines of longitude and latitude, and they have a unit, which are minutes, degrees, and seconds. These coordinates are represented on three images:

1. DMS: Degree Minute Seconds It is written as (27°12'25.2" N) the degree reads 27, 12, and 25.2 and the letter N is marked for north.
2. DDM: Degree Minutes It is written as '12.42°27'. It reads decimal degrees and minutes.
3. DD: Decimal Degrees The decimal degrees are written in the following form (° 27.12135).

The geographical system consists of:

•  360 longitudes (180 East + and 180 West -) separated by Greenwich Meter 0 represents longitude (long-X-).
• 180 latitudes (90 North + 90 South -) separated by the Greenwich line considered the number 0, representing the latitude (Lat-Y).

Measurement units :

• One degree = 60 minutes and = approximately 111.12 kilometers.
• One minute = 60 seconds and = approximately 1.852 kilometres.
• The second is the lowest unit = approximately 30.86 metres.

Important note: Degrees and minutes are valid numbers only, but the second number can be a valid or decimal number.

This geographic system uses a small scale to represent large geographic areas.

It takes into account the spherical shape of the Earth.

2. Projected Coordinate Systems:

It is called the projection because it is the geographical coordinates of the spherical surface that have been projected in the sense of converting it from a spherical shape to a plane that is drawn on a flat plate that does not represent the true shape of the globe, but it makes it easier for us to know every coordinate system for any country or geographical area in the globe.

They are orthogonal planar coordinates that are represented in meters or kilometers to express the location in a coordinate system according to any geographical area (1150 kilometers, 1150,000 meters).

The global coordinate system UTM is used, which is the global Mercator system, and every country in the world takes this system and adjusts it as it suits it to obtain more accurate maps of the global system, for example Palestine uses the projected Palestine Grid 1923 coordinate system.

• These coordinates are represented as E,W, East, West, or X,Y.
• The use of this system is considered in all accurate surveying operations.
• The sphericity of the Earth's surface is neglected.