What are Layers?

What are Layers?

Layers is a general term used to describe separate features on a map. If you take any map and break it down into parts you may notice that features “lay” in a certain order on top of each other. For example if you look at a road map of a city you can break it down into different parts. There are

Water bodies, parks, and jurisdictions represented by an area (polygon)
Streets, railroads, and trails represented by a line
and in this case fire hydrants represented by a point

How to create a map together

This is a basic primer into how a map is put together. In no way does this describes what totally happens, but is intended to give a general idea. However these principles are true whether you are a traditional cartographer or a GIS Analyst.

Creating an area map

The first thing you add to a map is the “base” layers. These layers are usually layers that are represented by polygons. Polygon layers are added at the bottom of a stack of layers.
Next what is usually added are the line layers. These could be layers like a street network as shown on the right or a perhaps a trail system. In GIS they can automatically “labeled” or manually “annotated” in this case to show the name of the street
Next you can add a point layer. In this case the point layer are some fire hydrants
Finally you combine all of the layer to create the desired map.