## What is the difference between geographic and projected coordinates?

A geographic coordinate system (GCS) is a reference framework that defines the locations of features on a model of the earth. A projected coordinate system (PCS) is flat. It contains a GCS, but it converts that GCS into a flat surface, using math (the projection algorithm) and other parameters.

### Should I use geographic or projected coordinate system?

Some are good for preserving areas on your map, others at preserving angles or distances. A projected coordinate system (PCS) is a GCS that has been flattened using a map projection. Your data must have a GCS before it knows where it is on earth. Projecting your data is optional, but projecting your map is not.

#### What are projection coordinates?

A projected coordinate system is a flat, two-dimensional representation of the Earth. It is based on a sphere or spheroid geographic coordinate system, but it uses linear units of measure for coordinates, so that calculations of distance and area are easily done in terms of those same units.

**What is the difference between geographic and geodetic?**

is that geodesy is the (l) discipline that deals with the measurement and representation of (l), its (l) field and (l) phenomena (polar motion, earth tides, and crustal motion) in three-dimensional, time-varying space while geography is the study of the physical structure and inhabitants of the earth.

**Is UTM a geographic coordinate system?**

Universal transverse Mercator (UTM) is a geographic coordinate system and the most prevalent plane grid system used. UTM divides the earth into 84˚ north latitude to 80˚ south and is numbered into 60 vertical zones (each 6˚ latitude wide). UTM uses transverse Mercator projection (conformal).

## What is the meaning of WGS 84?

World Geodetic System 1984

The World Geodetic System 1984 (WGS84) is a datum featuring coordinates that change with time. WGS84 is defined and maintained by the United States National Geospatial-Intelligence Agency (NGA). It is consistent, to about 1cm, with the International Terrestrial Reference Frame (ITRF).

### What GIS coordinate system does Google Earth use?

Mercator projection

Google Maps and Microsoft Virtual Earth use a Mercator projection based on the World Geodetic System (WGS) 1984 geographic coordinate system (datum). This Mercator projection supports spheres only, unlike the ESRI Mercator implementation, which supports spheres and ellipsoids.

#### How many types of geographic coordinate systems are there?

Horizontal coordinate systems locate data across the surface of the earth, and vertical coordinate systems locate the relative height or depth of data. Horizontal coordinate systems can be of three types: geographic, projected, or local.

**What are the most common geographic coordinate systems?**

Universal transverse Mercator (UTM)

Universal transverse Mercator (UTM) is a geographic coordinate system and the most prevalent plane grid system used. UTM divides the earth into 84˚ north latitude to 80˚ south and is numbered into 60 vertical zones (each 6˚ latitude wide).

**What’s the difference between a geographic and a projected coordinate system?**

Geographic coordinate systems span the entire globe (e.g. latitude / longitude), while projected coordinate systems are localized to minimize visual distortion in a particular region (e.g. Robinson, UTM, State Plane). Learn more about key differences between projected vs. geographic coordinate reference systems.

## What’s the difference between a datum and a projection?

A datum is a specific, known point on or in the Earth that is used for reference. A projection uses the datum as a point of reference, it’s location on Earth. In GIS, there are two types of “coordinate systems”: Geographic Coordinate System (latitude and longitude) and Projected Coordinate System (X and Y).

### How are data sources in a geographic coordinate system reprojected?

Data sources that are in a geographic coordinate system will be read and reprojected on-the-fly (OTF) to the chosen projected coordinate system. The project coordinate system is shown in the status bar. You can set or update the project coordinate system to any PCS that is applicable for your project area.

#### When do you use latitude and longitude coordinates?

Latitude and longitude coordinates are used to express points within a geographic coordinate system, such as NAD27 or WGS84. Meters or feet are used with projected coordinate systems, such as Alaska Albers Equal Area Conic.