Learning Objectives

After completing this lesson, you'll be able to:

• Distinguish between coordinates stored as numbers and spatial data stored as geometry.
• Explain the value of creating geometry from coordinates.
• Identify the types of data required to create geometry.
• List the 3 methods of converting coordinates into geometry.

What Is the Difference Between Coordinates and Geometry?

There are many ways to store information about the location of objects. One of the simplest is a coordinate: two numbers that represent a location on a two-dimensional plane.

A Cartesian coordinate system

For spatial data, coordinates are often stored using a geographic coordinate system, where each number in the pair represents the latitude and longitude of a point on the earth, respectively. For example, (49° 10' 48" N, 122° 50' 24" W) or as decimal degrees, (49.18, -122.84).

Latitude and longitude

They can also be stored in a projected coordinate system, where each number represents a location along a two-dimensional axis, similar to the Cartesian plane above.

One of the easiest ways to store coordinates is as numbers in a spreadsheet or table. This format makes them easy to enter and edit.

Example of coordinates stored in a table

However, in this format, the data cannot be directly displayed on a map as geometry because it lacks the data structure. Additionally, these simple numbers cannot be displayed as more complex geometry such as lines (connecting coordinate locations) or polygons (connecting them into a closed object). To display coordinates as points, lines, or polygons, you need to create geometry data.

You can learn more about coordinate systems in the Learn Spatial Data Concepts course or the page What is Spatial Data?

Creating geometry is a prerequisite to spatial data integration and analysis. If you want to take advantage of FME's features, you will need to turn your coordinates into geometry. Thankfully, it's a simple process!

What Methods Are Available?

Converting from CSV or Excel (or other non-spatial data) to point, line, or polygon features (also known as vectors) is easy as long as there is spatial data contained within the data, like latitude and longitude information or addresses. 

There are three different methods to create point features using FME: 

1. Using reader parameters. This method works well if you are going to be working with spatial data from the start. As of FME 2020, this method occurs automatically as long as the attributes are named correctly, such as latitude, longitude, and elevation, or x, y, and z. It is still possible to use this method in older versions of FME or if your attribute names are different, it just requires a manual step.
2. Using the VertexCreator transformer. This method is useful for when spatial data is added later on in the workspace, or if you are using a transformer that removes geometry.
3. Geocoding addresses using the Geocoder transformer. This method is useful if you do not have coordinates, only addresses. Depending on how many addresses are in your dataset, you may need to run this workspace multiple times over a series of hours/days or pay for a service as geocoding can be costly.

You will learn how to use all three methods In this course.