Chapter 10. What is geocoding?

Transcription

1 Chapter 10 Geocoding 10-1 Copyright McGraw-Hill Education. Permission required for reproduction or display. What is geocoding? The process of assigning a location, usually in the form of coordinate values (points), to an address by comparing the descriptive location elements in the address to attribute data present in reference data

2 Common applications of geocoding 911 emergency response Google Maps, Google Earth directions Mapping distribution of crimes Finding locations of customers Marketing analyses Finding locations of competitors Mass mailing Etc Addresses Addresses the thing you want to geocode They come in many forms Common address format: 701 S Mt Vernon Ave, San Bernardino, CA Postal Zone (Zip Code) City Cross Street

3 Reference data Data that your addresses are compared to Which data depends on the type of address Street Network City Boundaries Zip Code Boundaries Census Blocks States Countries Etc Geocoding requirements A table with address records to be matched A reference layer - spatial data containing features with attributes that addresses will be compared with An address locator set of rules and options guiding how addresses are compared with reference data

4 Address Locators A matching engine set up for a specific reference layer containing: Locator Style (US One Range, City/State, etc) Name and location of reference data Which attributes fields to use for matching Default options settings (can be changed during geocoding) Locators store a snapshot of the reference data Can be moved from folder to folder You don t need to copy the reference data with it If you edit the reference data you must re-create the locator Address Locator Styles Single Field US Alphanumeric Ranges US Cities with State US One Address US One Range US Streets US Hyphenated World Cities with Country ZIP 5-Digit and ZIP+4 With Zone

5 esri Address Locator Styles US Address City State US Address Dual Ranges US Address One Range US Address Single House US Address Single House Subaddress US Address Street Name US Address State US Address ZIP 5-Digit US Address ZIP+4 US Address ZIP+4 Range General City State Country General Gazetteer General Single Field 10-9 Matches a single field address to a single point or polygon. Most often used with parcel data. One Address Style

6 City State Style Matches two fields containing a city name and a state name or abbreviation Must match to points or polygons US One Range Style Similar to US Streets but does not consider left or right sides Requires a single address range for each street

7 US Streets Style Locates street address on both sides of the street using a line reference layer. Requires address ranges on both left and right side of streets in reference layer. Also called US Address Dual Ranges Geocoding Street addresses Addresses to be matched are parsed (split) into separate components (number, street direction, name, etc.) Each component of the address is compared to fields in the reference layer Candidates are scored based on how closely the components match (0-100) is a good match

8 Address components Prefix direction. 124 East Main St. Prefix type. 345 Highway 85. Number. 123 Maple St. Street name. 123 Maple St. Street type. 123 Maple St. or 15 Elm Ct Suffix direction. Florman St. E or 87th St. North City, State, Zip code. Optional How addresses are parsed Address Prefix Dir Prefix Type Number Street Type Suffix Dir 123 Maple Road 123 MAPLE RD 15 Center St. East 15 CENTER ST E 314 Hwy 85 N HWY N 234 E. St. Patrick St. E 234 SAINT PATRICK ST Notice that parsing includes converting to upper case

9 Reference layer 3120 NORTHLAND DR Point, line, or polygon features with attributes on which matching will be based Placing addresses 750 Meadowlark From: 700 } Offset Meadowlark St. To: Meadowlark

10 The geocoding process (In ArcMap) General geocoding process Create or obtain reference GIS data Determine an address locator style Create an address locator Add reference data to your map Add your address table to your map Set up a geocoding session Select your address locator to use Match your addresses in batch mode Review the matched/unmatched addresses Change geocoding options to facilitate matching Rematch addresses in batch or interactive mode

11 Setting up an address locator Setting up a locator Style Reference layer Matching fields Output

12 Using an Online Locator ArcGIS Online has a public domain locator. May not be as accurate as local ones, but provides easy access to large areas Only available for single addresses (not tables) without a subscription Composite address locator Address locator containing two or more individual address locators, ex: a street address locator a ZIP Code locator Allows addresses to be matched against multiple locators and find the best matches If an address fails to match against the street address locator, the address can fall back to match against the ZIP Code locator

13 Starting a geocoding session Geocoding options Alternate table 5 th & Main Alias table These options can also be changed during a geocoding session

14 Geocoding toolbar Turn on geocoding toolbar for re-matching and address exploration options Reviewing / Re-matching 1. Locator will attempt to match the addresses in batch mode. 2. It will give you this report when it is finished. 3. If everything was matched, click Close. 4. Most likely, though there are unmatched addresses. Click Rematch

15 Interactive re-matching Change to Unmatched Addresses Reduce width of fields to see addresses Looking for candidates Select row to hunt for candidates Examine standardization Edit problems Adjust options

16 Adjust geocoding options Adjust spelling sensitivity and add a place name alias table Match best candidate Close when done

17 Finished result! Rematching You can rematch an already geocoded layer to try to rematch more addresses

18 END