4 In the Contents list, click California Health Indicators (not its check box) and then % Overweight by School. The map legend shows the classifications for the number of overweight children by school.
5 Click the Show Map Legend button . The resulting map has a nice legend and is a detailed map.
YOUR TURN
Zoom in to see school names displayed on the map. Change the basemap to see street-level details. Zoom back to the San Diego Bay area. Change the basemap back to Terrain with Labels.
Explore a layer description
1 Click the Show Contents of Map button .
2 Click the arrow to the right of the Terrain with Labels layer and select Description. A web page describing the basemap layer appears.
3 Scroll to read the entire map description. When you are finished, click the Map link to go back to the ArcGIS My Map page.
Save the map
1 On the Map toolbar, click the Save Map button and then Save.
2 In the Title box, type Overweight Children By School and for the tag, type obesity.
3 In the “Save in folder” box, select your ArcGIS Online Account.
4 Click Save Map.
YOUR TURN
Select Add and Search for Layers. Type food as a layer to search for in ArcGIS Online and add the food layers called Supermarket Access Map Service and USA Farmers Markets map service to your map. The latter map service contains locations of farmers’ markets as reported to the US Department of Agriculture (USDA). Zoom to various areas of California and see if there is a correlation between overweight children by school and access to supermarkets and farmers’ markets. Practice turning layers on and off. Save your map as a new map called Overweight Children Compared to Food Sources with the tags obesity, food.
Tutorial 1-7
Using maps on a smart phone and tablets
Free ArcGIS apps are available from Google Play, the Apple App Store, Amazon Appstore, and Windows Marketplace. In these exercises you learn how to use the ArcGIS app on the iPhone but similar steps can be used on other smart devices. Open a map in ArcGIS Explorer Online
1 Search for ArcGIS at the Apple App Store and install Esri ArcGIS on your iPhone.
2 Open the Esri ArcGIS app.
3 Click the Sign In button.
4 Enter your ArcGIS Online (Esri account) username and password.
5 Click the icon in the upper left corner of the app.
6 Click My Maps.
7 Click the second map, Overweight Children Compared to Food Sources map. The map opens on your iPhone.
8 Use usual iPhone gestures to zoom in or out and pan to the Naval Base in San Diego, near the San Diego Bay.
9 Click the Identify button on the lower left of the screen. This provides access to three buttons: Legend for the map legend, Content for the table of contents, and Detail for documentation.
The legend appears by default.
10 Click the Content button. The layers you added in ArcGIS.com appear. You can turn layers on and off and change the basemap. The Detail button will show documentation about the map creation.
11 Click the Map button at the top left of the screen. You now see your map again.
YOUR TURN
Explore other smart app functions such as Measure Distance, Measure Area, and Bookmarks found on the top bar of the app.
Summary
GIS is a fascinating and valuable information technology, enabling spatial processing and visualization of data in ways never before possible. At the most basic level, GIS makes it easy to quickly compose and render maps from base layers. You can easily turn map layers on and off to study spatial patterns and correlations. You saw how GIS connects visual maps and underlying attribute data when you labeled map features and used choropleth and graduated point marker maps to render numeric scales for variables. In later tutorials, you will discover additional powerful uses for attribute data connected to map features.
Three components make GIS analysis possible for applications such as health care. The first is the national map infrastructure — a collection of basemaps, census and other data, and geocodes for uniquely identifying areas. In the United States, this resource is a public good, paid for by tax dollars and available for use at no or nominal cost. Commercial map layers are also available at reasonable cost and in many cases are essential for applications. This chapter introduced important components of map layers, including geographic and rectangular coordinate systems, projections between the two types of coordinate systems, and map scale.
The second component necessary for applications is user-friendly and powerful GIS software. ArcGIS for Desktop is the software used in this book. This chapter covered the primary uses and interfaces of the two major ArcGIS application packages: the ArcCatalog utility for browsing and maintaining spatial data files and ArcMap for creating maps and analyzing data. This chapter asked you to examine the input map layers and GIS data for studying lung cancer mortality in white males. The spatial patterns you observed suggest possible correlations within the mortality data, including poverty, tobacco growing, and coal mining.
The third component explores online GIS tools developed by Esri — ArcGIS Online. Although the analytic capabilities of these tools are not as advanced as desktop GIS, they are easy to use and enable beginning GIS users to work with, share, and explore existing map layers related to various health conditions such as obesity.
We should probably add a fourth component that is necessary for successful GIS applications: GIS analysts. Knowing how to use GIS is not a common skill, and there is a lot to learn. Nevertheless, this book will help you use GIS productively and efficiently,