Why coordinate system important

Since there is no perfect way to transpose a curved surface to a flat surface without some distortion, various map projections exist that provide different properties. Some preserve shape, while others preserve distance. Some preserve area or direction.

The extent, location, and property you want to preserve must inform your choice of map projection. There are more than 4, coordinate systems in the ArcGIS platform, so it is likely you'll find one to match your data.

If not, you can create a custom coordinate system to display the data. ArcGIS Pro reprojects data on the fly so any data you add to a map adopts the coordinate system definition of the first layer added. As long as the first layer added has its coordinate system correctly defined, all other data with correct coordinate system information reprojects on the fly to the coordinate system of the map. This approach facilitates exploring and mapping data, but it should not be used for analysis or editing, because it can lead to inaccuracies from misaligned data among layers.

Data is also slower to draw when it is projected on the fly. If you intend to perform analysis or edit the data, first project it into a consistent coordinate system shared by all your layers. This creates a new version of your data. Download the list of supported projected coordinate systems. See a list of all the supported map projections. After defining the coordinate system that matches your data, you may still want to use data in a different coordinate system.

This is when transformations are useful. Transformations convert data between different geographic coordinate systems or between different vertical coordinate systems. From the Equator a series of parallel lines were recognised with the most northern and southern points being called the North Pole and South Pole. Because lines of latitude are like slices through the Earth they have different lengths. For example:. Defining longitude was much more difficult, as it is could not be based on observations of movement of the sun.

The convention eventually agreed upon was to have a series of radiating lines which run vertically around the Earth. They connected at both ends — i. These are pointed at their ends and broadest in the middle. For a considerable period of time the issue of which line of longitude was to be the primary line could not be agreed. For obvious religious reasons, early European maps often used Jerusalem as the primary line of longitude.

Because of its status as a centre of learning other early map makers, such as Ptolemy , had used Alexandria in Egypt.

More commonly though, for patriotic reasons, many countries chose one of their cities. Eventually, in October , at the International Meridian Conference, it was agreed that the line of longitude that runs through the Royal Observatory, Greenwich in United Kingdom, was to be adopted as the standard primary line of longitude. Combine latitude and longitude together and we have a system to record the location of any feature on the surface of the Earth uniquely. These are:.

Note with this definition continental Europe is in the Eastern Hemisphere. Finally, there are also two South Poles — Geographic and Magnetic. How can you find your location? Absolute location: exact spot on the planet where something resides Latitude and longitude.

Learning about longitude and latitude By the time you are finished with this power point you should know the difference between longitude and latitude. Similar presentations. Upload Log in. My presentations Profile Feedback Log out.

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