Overlay Layers

Overlay combines two or more layers into one single layer. You can think of overlay as peering through a stack of maps and creating a single map containing all the information found in the stack. Overlay is much more than a merging of line work; all the attributes of the features taking part in the overlay are carried through to the final product. Overlay is used to answer one of the most basic questions of geography, "What is on top of what?" For example:

If Use current map extent is checked, only the features in the analysis and overlay layer that are visible within the current map extent will be overlaid. If unchecked, all features in both the analysis layer and the overlay layer will be overlaid, even if they are outside the current map extent.

Choose overlay layer

The layer to be overlaid with the analysis layer.

Choose overlay method

The overlay method defines how the analysis layer and the overlay layer are combined.

  • Intersect—The result will contain only those features or portions of features in the overlay layer that overlap with features in the analysis layer. When intersecting line or area features, you have the option to specify the type of features you want as output.

    Points with Points

    Points and points input

    Points and points with point output

    Points with Lines

    Points and lines input

    Points and lines with point output

    Points with Areas

    points and areas input

    		points and areas with point output

    Lines with Lines

    Lines and lines input

    Lines and lines with point output

    Lines and lines with line output

    Lines with Areas

    Lines and areas input

    Lines and areas with point output

    Lines and areas with line output

    Areas with Areas

    Areas and areas input

    Areas and areas with point output

    Areas and areas with line output

    Areas and areas with area output

  • Union—The result will contain features from both the analysis layer and the overlay layer. The Union option is only available if both the analysis layer and the overlay layer contain area features.
  • Erase—The result will contain features or portions of features in the overlay layer that do not overlap with the areas in the analysis layer. The overlay layer can contain area, line, or point features.

If Use current map extent is checked, only the features in the analysis and overlay layer that are visible within the current map extent will be overlaid. If unchecked, all features in both the analysis layer and the overlay layer will be overlaid, even if they are outside the current map extent.

Result layer name

This is the name of the layer that will be created in your My Contents and added to the map. It will have the same feature type (areas, lines, or points) as the overlay layer. The default name is based on the overlay method and the analysis layer name. If the layer already exists, you will be asked to confirm if you want to overwrite it.

Using the Save result in drop-down box, you can specify the name of a folder in My Contents where the result will be saved.