Fixed Zoom Out You probably noticed that no streets were visible at the global scale, and that as you kept zooming in, more and more detail appeared. This is because the basemap is a multiscale map—really, a set of maps that turn on and off to display features and symbology that are appropriate to your map scale.
The figure shows Greater Los Angeles, an area that includes scores of incorporated communities and nearby cities.
Basemap layers
Basemap layers show reference geography such as street maps, imagery, topography, and physical relief. The ones available in ArcGIS Pro are remotely hosted map services that you can navigate, view, and use as backdrops to other data. Basemaps are stored at multiple scales, so that as you zoom in or out, you see different amounts of detail. As you navigate a basemap, the various pieces of it (called tiles) that compose your current view are stored locally on your computer in a “display cache.” When you zoom or pan to a new area, the map may be a little slow to draw, but anyplace you return to will redraw quickly, because the data comes from your cache, not from the remote server.
Add a layer of project data
On top of the basemap, you’ll add a layer from the data that has been put together for this project and is stored on your computer. In lesson 2, we’ll talk more about where this data comes from and how to acquire data of your own.
1)In the Catalog pane, right-click Folders and click Add Folder Connection.
2)Browse to your UGIS4 folder and select the ParkSite folder. Then click OK.
Selecting a folder adds a new folder connection to ParkSite.
3)After making the folder connection, expand ParkSite\SourceData and then ESRI.gdb, and finally the Boundary item.
4)Drag the City_ply layer to your map. Default layer colors vary, so don’t worry if the color of your layer looks different from the figure.
We’ll discuss GIS data formats in the sidebar “Representing the real world as data” in lesson 2. For now, you just want to dig down to your data.
When the layer of city boundaries is added to the map, it may zoom to the full extent of the dataset. If so, click the Previous Extent button
Each city in the layer is called a feature. These features are polygons, which are one of the three basic shapes used to represent geographic objects in a GIS. (The others are lines and points.)
In the Contents pane, the order of entries matches the drawing order of layers in the map. City_ ply is listed above World Street Map, and on the map, the cities cover the basemap. You can control a layer’s visibility with its check box in the Contents pane.
5)In the Contents pane, select the check box next to City_ply.
The layer is turned off.
6)Select its check box again to turn the layer back on.
Set layer properties
Every layer has properties you can set and change. For example, you just changed the visibility property of the City_ ply layer.
1)In the Contents pane, right-click the color patch underneath the City_ply layer name. A color palette opens. Pointing to any color square shows its name as a ToolTip.
2)On the color palette, click Olivenite Green.
On the map, the cities redraw in the new color.
3)In the Contents pane, right-click the City_ply layer name to open its context menu. At the bottom of the menu, click Properties.
The Layer Properties dialog box opens. Here is where you access the full set of properties for a layer.
4)If necessary, click the General tab at the top of the left column on the dialog box.
The layer’s name, City_ ply, is one of its properties. This name is cryptic (it stands for “city polygons”) and unattractive, so now you can change it.
5)In the Name box, delete the text and type Cities.
6)In the Layer Properties dialog box, click the Source tab.
This tab shows technical information about the layer, including the path to the data on your computer.
7)Click OK on the Layer Properties dialog box to close it.
Notice that the name is updated in the Contents pane.
Renaming the layer in the map simply makes it easier to identify in the map. It doesn’t change the source data file’s name (which is still City_ ply). A layer is a representation or rendering of the data, not the data itself. You can make any changes you want to a layer’s properties without affecting the data on which the layer is based.
Get information about cities
Now see what you can find out about the cities on the map.
1)Click any city polygon on the map.
The city flashes blue, and a pop-up window opens. In the title bar of the pop-up window, you see the name of the city you identified. In the pop-up window, you see its attributes, or the information that this layer stores about cities. Some of the attributes aren’t obviously meaningful, but others are. If POP2010 is population for the year 2010, and POP10_SQMI is population per square mile for the same year, you know that Los Angeles (if that’s the city you identified) had 3,792,621 inhabitants at the time of the 2010 census, and its population density was 8,018 people per square mile.
2)If necessary, move the pop-up window away from the map. Identify a few more cities.
The pop-up window updates with information about the new city. All the cities have the same set of attributes; it’s the values of the attributes that change.
3)Close the pop-up window.
