Geocoding is a fairly straightforward process in GIS software such as Esri’s ArcGIS Pro. However, default geocoding locators or settings may be insufficient depending on the type of data to which you have access. For example, if a police department’s geocoding relies solely on a street centerline locator, specific addresses/locations will likely be inaccurate.
Consider the following example:
- A police department uses only a street centerline locator. This means any addresses to be geocoded will be approximated based on the centerline information.
- An armed robbery occurred at 1250 Main Street.
- Geocoding this offense will result in putting the crime directly in the middle of the 1200 to 1300 block of Main Street. This is because the “50” of “1250” is numerically halfway between 1200 and 1300.
- In reality, the address is located at the end of the 1200 block, not in the middle of it.
- The end result is a geocoded crime that is not wholly accurate.
Creating a Composite Address Locator can help alleviate this issue. As its name suggests, a Composite Address Locator combines multiple, individual locators into a single geocoding tool. Returning to the armed robbery example above, a Composite Address Locator could run the offense’s location through a parcel-based locator, a specific address locator, and a street centerline locator, one after the other. The idea is the highest-scoring match from a given locator is then applied to the data being geocoded.
The following steps will walk you through the process to create a Composite Address Locator in ArcGIS Pro. Note these steps assume you have already obtained or created the individual locators you will include in the Composite Address Locator. For example, your city’s or county’s GIS department may have street centerline or specific address/parcel locators.
- Open the Geoprocessing pane, if necessary, and select the Toolboxes header.
- Scroll down to Geocoding Tools, then double-click the Create Composite Address Locator tool.
- The Create Composite Address Locator tool opens.
- Click the Browse icon found next to the first blank box under Address Locators. Note it looks like an open folder.
- You will now navigate to the location where you saved the individual locators mentioned before step 1. Note the locators use the “.loc” file extension and are listed as “Locator” under the Type header.
- Select as many of the individual locators as needed, then click OK.
- The individual locators are added to the Create Composite Address Locator tool. There are three locators in this example but there may be more or less based on your workflow.
- Note the order in which the locators display in the Create Composite Address Locator tool determines the order in which they are used while geocoding data. The order can be changed, if desired. This will be covered shortly.
- Review the contents added within the Field Map portion of the Create Composite Address Locator tool, including the Input Fields and Subfields.
- The Create Composite Address Locator tool automatically configures this information. In most instances, including basic geocoding needs, the automatic settings will likely be correct. However, it is worthwhile to ensure the Input Fields match your expectations. Otherwise geocoding results may be inaccurate or otherwise not meet your needs.
- The picture below shows Input Fields for Address, Address2, Address3, Neighborhood, and so on.
- Clicking the first “Address” header under Input Fields shows all three locators have “Address” in their background data, as found under the Subfield header in the graphic below. This is the desired setting for this Input Field.
- Repeat the previous step for each input field and confirm settings are correct.
- The Selection criteria section can be modified but these settings are optional. Default settings will be used for this example. Click here to learn more about selection criteria, if needed.
- Click the Browse button next to the box under Output Composite Address Locator. Navigate to a directory where you want to save your new Composite Address Locator. The same directory containing individual address locators used previously is used for this tutorial but any save location will work.
- Name your new Composite Address Locator and click the Save button.
- The last setting to configure is adjusting the result order of the Composite Address Locator, as mentioned earlier in step 7.a.
- The default setting is “Use locator order.” If this is acceptable, proceed to step 14.
- To change the result order, click the dropdown arrow under Select Result Order and choose Custom order. Your individual address locators should display automatically, as shown below.
- Click the up or down arrows for each address locator to meet your preferences. In this example, the street centerline locator was moved from the middle position to the bottom
- Confirm all settings within the Create Composite Address Locator tool are correct, then click the Run button to create your new Composite Address Locator.
- ArcGIS Pro will display a message indicating the tool has finished and your new Composite Address Locator was successfully completed.
- Note your new Composite Address Locator is also visible in your ArcGIS Pro project’s Locators folder within the Catalog, assuming you saved it in the default Locators folder as shown in step 12.
- You can adjust any other settings for the Composite Address Locator by right-clicking the locator and selecting Locator Properties. Click here for more information on adjusting Locator Properties.
- You are now set to use the Composite Address Locator for any future geocoding needs! The locator created in this example will run each data point’s address information through a master list of addresses, followed by a secondary structure address list, and finally the street centerline information.
Accurate address data is critical to good analysis, whether it be plotting the features of your environment which may act as crime attractors, to ensuring that your incident data is properly projected so the results of your analysis are as accurate as possible. As explained at the beginning, some of the data to which you have access may be great for one purpose – street centerlines are what you need to drive to an address in a hurry. But you want your analytic models built using any software program or tool you have at your fingertips to be correct, easily understood and actionable by your organization.