Building a Map with Layers

Maps you create in the GIS Editor will contain one or more layers. A layer can be thought of as a container for geographic data that is alike. For example, you might have a layer containing roads, another containing rivers and still another containing cities. A layer gets its data from a data source, which can be a file containing vector information (for instance, Shapefiles or Tab Files), raster imagery (i.e., satellite photos) in formats like GeoTIFF, or even Web Map Services like Bing Maps, OpenStreetMap or ThinkGeo's World Map Kit.

Each layer can contain one or more features, and each feature consists of one or more shapes that go together. Shapes typically come in one of three types: points, lines and areas (or polygons). One feature does not necessarily need to correspond to one shape; a single feature might contain a whole group of areas which together represent a place. As an example, a feature representing the country of Australia might contain dozens of areas, including numerous outlying islands or other areas that are not physically connected.

Every feature is linked to information that is stored in your layer's data source. This information usually includes coordinate data that identifies the exact size of the feature and its location on a map of the world. Other types of information may also be included, such as the population for a city feature, the name of a county area feature, or the highway number for a road feature. All of this data is collectively stored in a table that looks very much like a spreadsheet.

As you add layers to your map, they are added to the GIS Editor's Layer List panel. The Layer List shows you all the layers of your map in the order in which they are drawn, and allows you to control which data is drawn above or below other data on your map. For instance, it's likely that you would want roads drawn on top of country landmasses, otherwise the countries would cover up the roads and prevent them from being seen. Each map you create within a project in the GIS Editor has its own layer list.

If you have data on your computer in a supported format, such as a Shapefile, there are two main ways to add it to your map as a new layer. You can:

• Click the “Add Layers” button on the ribbon bar.
• Find the data file in your Data Repository and double-click on it.

The Add Layers button on the ribbon bar allows you to quickly add a new layer to your map by browsing your computer for a support file type. Using the standard Windows Explorer interface, you can browse your computer or any network location for data. You can click the top half of the button to browse for files of all formats that are supported by the GIS Editor. If there is a specific format you're looking for, click the bottom half of the button to open a dropdown menu, then choose one of the listed formats.

Once you have found the data you want to add, simply double-click on it to load it onto your map as a new layer.

When you load a file this way, you may be asked if you would like to add the file to your Data Repository. Adding the item to your repository is handy if you would like to access it more quickly in the future.

The Data Repository is an easy way for you to aggregate sets of data from different locations in one easy-to-use list. If the data you want to add to your map is already in your Data Repository, simply locate it and double-click it to load it onto your map as a new layer.

Using the Data Repository, you can load vector data, raster data or Web Map Services (also known as Base Maps).

You can add a new empty layer to your map and begin creating new data from scratch. To do this, follow the steps below:

1. On the GIS Editor's ribbon bar, click the Edit tab.
2. In the Editing Tools group, click the “New Layer” button. The Define Layer Columns dialog will appear.
3. Using the Define Layer Columns dialog, configure the data options for your new layer and then click OK.
   1. Layer Type lets you define whether this will be a Point, Multipoint, Line or Area (polygon) based layer.
   2. Layer Name lets you choose a name for your layer. This name will be used for the output file and will also appear in the Layer List.
   3. Use the “Add New…” button to set up data columns for your layer. Think of your layer as a spreadsheet, with rows and columns that define each shape on the layer. Columns are usually used to define attributes for each shape – for example, the population of a city or the name of a country.
   4. Output folder lets you select where to save the file that contains the data for your new layer.
4. To add the layer you just created to your map right away, click Yes when prompted.

You should now see your new layer at the top of your Layer List. From here, you can start adding features to the layer using the editing tools. See the topic “Drawing New Features” to learn how.

Styling, organizing and arranging layers on your Layer List are the main ways of controlling the appearance of your map. For more information, take a look at the following articles:

• Using the Layer List
• Layer Groups
• Applying Styles