Why are coordinate systems important in GIS?

What are the three types of coordinate systems in GIS?

That's the kind of question that really makes me cringe.

I'm sure some would argue for all 3, but as a beginner there's really only 2 choices that make sense. I would say use whatever is the easiest for you.

There's basically 2 kinds of coordinate systems that people use in GIS; map projection and model coordinate. Map projection (like NAD27) is just a way to get your points from one place to another. When I started learning GIS it was all about map projections. When were teaching map projections it was all about how to get points from one place to another using different projections. That was the whole point. But then people started to use models where your points are defined within some model (worldwide, UTM etc). The problem with models is that the only coordinate system they're based on is that model and you can't do anything with them without knowing their coordinate system.

Your first task is to decide which kind of coordinate system you want to work in. If you want to work in a worldwide coordinate system you need to decide on a type of model and select that model in your toolbars. If you want to work in UTM for the US then you need to select that in your toolbars.

In ArcGIS Desktop a great tool to use to understand your coordinate system is "Data Management Tools". I find it really helpful.

What are the 4 components of a geographic coordinate system?

There are four components of a geographic coordinate system: Longitude and latitude - which represent the center of the plane in the x & y directions.

Axis rotation - which aligns your plane to it's proper orientation. Projection - which determines how many kilometers away on the surface of the earth we're talking about. Origin - where we put the point that shows up on the surface of the earth as the origin. For example, if you put the point 0,0 at the north pole, and then you say what latitude and longitude of points do you get? Well, any point on the surface of the earth that is north and 0 degrees longitude. So you can see that the coordinates you get using those four components define any point on the surface of the earth with those latitudes and longitudes, which is actually the same as saying there is a straight line through this point on the map that is perpendicular to that plane and points to 0,0. The reason we say perpendicular is that this is a geometric proof and one of the reasons these four things are given names (longitude/latitude/axis rotation/projection) is because you can look at them and prove that they are all perpendicular to each other, but why should we know that or care about that at this point? In a future lesson, we will learn about how to deal with projections, which we'll do in a later section of the lesson, but for now, we'll understand how to get the latitude and longitude of points so they can be mapped onto our flat earth.

Remember that latitude and longitude start at the equator and end at the poles so this is why you need to know what the north pole is. In this case, the poles are 0,0 or, if you want to be more technical, in a plane parallel to the equator with the equation x=0 and y=0 so both are equal to zero. If you look at your standard compass you'll notice it has an arrow pointing to the north and it shows that you are exactly 90 degrees from the equator, or north, if we're doing this correctly. If that's wrong then use your own compass (or phone or camera or GPS. Whatever.) as there are plenty of them out there).

Why are coordinate systems important in GIS?

In the old days when everyone used to collect data in a flat file with a unique structure and when it was collected by a data processing application and the final delivery was done with the help of a data base, the only requirement was that this data should be kept in that unique format.

That time when the number of applications that have their own coordinate systems and their own formats were still very less in the market. Today, many organizations are using GIS which is more complex in its structure and operation.net then the complexity of a GIS is not a big deal. Because in a GIS the information is stored in the form of databases and the data is structured in a way that even the data processing application is able to understand. But when it comes to the GIS itself, it is not necessary that all the data in the database should be there or if it is there then the data can be represented in a specific way to make it easier for the processing. For example if you want to store the data in a table in the database but you want the data to be displayed in a different way or if you want to process the data from one of the files on the hard disk and you want to merge the processed data into another file on the hard disk, then we need a coordinate system where we can store this information.

In my career I have worked on many GIS projects and I have been assigned the responsibility of providing them with the right coordinate systems. There is a common misconception that if you are providing a GIS to any organization, then you are required to use the same coordinate systems that are provided by the government organizations or the public transport authorities. But it is not true. We as GIS professionals or data geographers, are not allowed to use the coordinate systems of the government or private organizations in our GIS. Because we do not want the data to be misused in a wrong manner. So if you want to use a different coordinate system for your own information and analysis, then you are doing the right thing. But we would like to give a few examples of the reasons why it is a good idea to use different coordinate systems.

Imagine if you want to use a coordinate system that is more suitable for your local conditions.