Maps Disclaimer

You can turn an individual layer on or off by clicking on the adjacent checkbox. A layer is 'on' (displayed on the map) when there is a check in its checkbox. Some layers are only available at certain scales. Layers that are available at the current scale will be shown with a light blue identify icon next to the layer name, while layers that are unavailable at a given scale are shown with a grey identify icon next to the layer name.

A layer is made 'Active' by clicking on the icon adjacent to a layer name. A dark blue icon denotes the active layer, and its name is displayed in the area below the map window. You can only have one active layer.

This means that the spotlight is on this layer. In other words, this is our way of telling the computer that this is the layer in which we are interested. How is this relevant, you ask?

Wow, you ask a lot of questions. Read on.

Identifying Features' Attributes for an Active Layer

The introduction to GIS Concepts section discussed layers and how features have attributes in a GIS.

Suppose you are interested in the elevation of a particular location into which you have zoomed. First, you ensure that the layer with elevation attributes is the active layer (see the above lesson to do this). In this case, the 'Contours' layer is made active.

The Identify tool allows you to get attribute information about a feature by clicking on it. You select the Identify tool to click on the feature whose attributes you want to examine.

The attributes for that feature are displayed in a new window. If the window does not appear, make sure that the feature you are clicking on is part of the layer that is active.