Changing Coordinate System and Projection

Coordinate system and Projections are most important part of any Map. This helps in in determining the location of any object on the map. There are various coordinate systems and projections. Even if the files are having geographical reference and they are of same region, they may not overlap due to different projection.  Simplest way to definition as follows.

Coordinate System: A reference system with which every location(point) on the surface of the earth can be located using intersection of a latitude(easting) and a longitude(northing). 

Projection: It is the method of representing 3D earth surface on 2D paper.

You can further study about Coordinate System and Projections at your free time to get a detailed understanding.

It is very likely that various maps, satellite images, DEMs, GPS coordinates be in different projections and hence they do not overlap. So it is always advisable to have all the files of a project in the same Coordinate System and Projection. So there would be a need to change Coordinate system or Projection of one file into another. Below is the video which illustrates on how to change projection from one to another.

Notes and Tips:

• Just try to understand the basics of the projection and coordinate system you are going to retain in your project, that will help you in taking the best decision to select the projection and coordinate that suits best to your work.

• It is always better to import the projection from another file than defining on your own, as there are possibilities of human errors while you define on your own.

• in ArcMap version above 10 importing Projection from another file is slightly different than in 9.3. In the window there is a small down arrow next to the globe symbol in the search row. When you click on that, you will get the option "Import"