Overview

You will learn: how to use the Map Viewer analysis tools to overlay, intersect, and merge features.

ArcGIS Online includes a powerful set of tools for performing spatial analyses and managing data. A common spatial analysis operation is to overlay (intersect and merge) two layers to find intersecting features and then use the resulting features and attributes to help with map visualization or to perform further analysis. For example, you may want to find all features that intersect a zip code, county, or city boundary, merge the data, and discard all of the others. This operation can be accomplished in the Map Viewer with the Overlay Layers tool. The tool requires an input layer (the layer you wish to extract features from), an overlayer layer (the layer defining the area to extract), and a specified overlay (merge) operation: intersect, union, or erase. The overlay operation determines how features are extracted and how the attributes are merged together. The result is a new hosted feature layer.

In this lab you will use the Overlay Layers tool to intersect and merge zip codes with different datasets in the Santa Monica Mountain area.

Steps

Create a copy of the web map

  1. Go to the LA Parks and Trails Map web map and click Sign In.

  2. Click Save > Save As > Save Map to save a copy.

Add the USA Zip Code layer

  1. In the top bar, click + Add > Search for Layers:

    • Find: USA Zip Code Boundaries 2016
    • In: Living Atlas Layers
    • Click United States ZIP Code Boundaries 2016 > Add > Done Adding Layers.
  2. In Contents, click United States ZIP Code Boundaries 2016 > ... > Move Down (or drag) to move the layer under Parks and Open Spaces.

  3. Uncheck all of the layers to make them invisible except the Boundary layer.

Intersect polygons with a polygon

Use the Overlay Layers tool to intersect the USA ZIP Code Boundaries 2016 layer and the Boundary layer to find which zip codes are in the boundary.

  1. In the top bar, click Analysis.

  2. In the panel, click Manage Data > Overlay Layers and select the following:

    • 1. Click United States ZIP Code Boundaries 2016
    • 2. Click Boundary
    • 3. Click Intersect
    • Output: Areas
    • 4. Change the layer name to: Zip Codes in Boundary
    • Click Run Analysis to create the layer.
  3. In Contents, uncheck the Boundary layer to make it invisible.

  4. In the map, click on some features and view the zip code data.

Intersect lines with polygons

Use the Overlay Layers tool to intersect and merge the Zip Codes in Boundary and the Trails layer.

  1. In the top bar, click Analysis.

  2. In the panel, click Manage Data > Overlay Layers and select the following:

    • 1. Click Zip Codes in Boundary
    • 2. Click Trails
    • 3. Click Intersect
    • Output: Lines
    • 4. Change the layer name to: Trails with Zip Code
    • Click Run Analysis to create the layer.
  3. In Contents, click Trails with Zip Code > Change Style and select the following:

    • 1. ZIP_CODE
    • Click Done.
  4. In the map, click on some trail features to view the merged zip code data.

  5. In Contents, uncheck all fo the layers to make them invisible.

Intersect polygons with polygons

Use the Overlay Layers tool to intersect and merge the Zip Codes in Boundary and the Parks and Open Space layer.

  1. In the top bar, click Analysis.

  2. In the panel click Manage Data > Overlay Layers and select the following:

    • 1. Click Zip Codes in Boundary
    • 2. Click Parks and Open Space
    • 3. Click Intersect
    • Output: Areas
    • 4. Change the layer name to: Open Space with Zip Code
    • Click Run Analysis to create the layer.
  3. In Contents, click Open Space with Zip Code > Change Style and select the following:

    • 1. ZIP_CODE
    • Click Done.
  4. In the map, click on some features and view the merged data.

Congratulations, you're done!

Your web map should look something like this.

Challenge

Intersect data with a Map Notes graphic

Use the Map Viewer to create a Map Notes layer and manually draw a polygon graphic that can be used to intersect the Trailheads layers. The polygon should represent an area that overlaps the trailheads that you would like to merge and extract. Use the Manage Data and the Overlay Layers tool to perform the intersection.

Learn more about how to create Map Notes and graphics in the Draw graphics lab.