GPS Coordinate System (WGS Coordinate System | EPSG:4326)

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Introduction

GPS Coordinate System, that is, the coordinate system used by the Global Positioning System, is usually based on the geographic coordinate system (EPSG:4326) WGS84 (World Geodetic System 1984). This is a universal reference system used to determine the longitude and latitude of any point on the earth. WGS84 is a geocentric coordinate system with the center of mass of the earth as the origin. It is widely used in navigation, surveying, mapping and geographic information systems (GIS).

Data Format Overview

Coordinates are expressed in the form of longitude and latitude, and some applications will come with altitude information (ellipsoidal height) in meters. Its storage format is:

**Text format: **In file formats such as GeoJSON, CSV, KML, etc., WGS84 coordinates are directly saved as values.
**Database format: **In PostGIS, WGS84 is usually saved in the form of SRID 4326, which supports complex spatial analysis and queries.
**Standardized encoding: **EPSG:4326 is an internationally accepted code identifier used to mark geographic data using the WGS84 coordinate system.

Pros

1. Globally applicable: WGS84 is an international standard and is compatible with all mainstream navigation systems (such as GPS, GLONASS, BeiDou).

2. High-precision reference ellipsoid: Based on the geocentric design, the reference ellipsoid of WGS84 has a high fitting accuracy with the true shape of the earth and is suitable for global applications.

3. Widely supported: Most GIS software, navigation devices, and map services (such as Google Maps, OpenStreetMap) are natively supported.

4. Easy to understand: The representation of latitude and longitude is intuitive and suitable for describing the absolute position of any point on the earth’s surface.

Cons

1. Non-planar coordinate system: Latitude and longitude coordinates are based on the sphere and cannot be used directly to measure plane distance or area. Projection conversion is required.

2. Regional accuracy differences: WGS84 is a global system. For local areas (especially high-precision measurement scenarios), it may not be as accurate as regional coordinate systems (such as China’s CGCS2000).

3. Deviation from the actual terrain: Altitude information is based on the ellipsoid model and is different from the actual terrain (such as altitude).

Application Scenario

The WGS84 coordinate system (EPSG:4326) is widely used in various geographic data applications. In navigation and positioning systems, it is used to describe the location of vehicles, aircraft, ships, etc. on the earth and supports real-time trajectory tracking. In online map services (such as Google Maps and Bing Maps), it is the basis for data storage and presentation, and is used to provide geographic positioning and path planning functions. In geographic information systems (GIS), WGS84 is used as a global benchmark for integrating and sharing geographic data from different sources. In environmental monitoring, logistics and transportation, military reconnaissance and other fields, it is used to capture and analyze dynamic changes on the earth’s surface. In addition, with the popularization of the Internet of Things and drone technology, the importance of WGS84 in location services and remote perception is also increasing.

Example

WGS84 ellipsoid.

Worldwide geometric satellite triangulation network, BC-4 cameras.