GTECH 709 Geocoding and address matching What is

GTECH 709 Geocoding and address matching What is a census? Decennial census Census geography framework

Geocoding • The process of assigning a location to an address by comparing the descriptive location elements in the address to those present in the reference material

Address Processing

Address Basics • What is an address? • Address elements • Address formats

Address Reference Systems Axial Based on a set of base lines that define the starting points for numbering Often the basis for a “grid” type system Linear Non-Axial Numbering is based on the distance along a specific street Where streets follow contours, change direction frequently Area-based Numbers assigned within a specified area by other method (example: mobile home parks, campgrounds) May use lot numbers, chronological order, other

Address Grid Example Axis Lines East 1000 East 2000 East 3000 North 2000 Point of Beginning North 1000 South 2000 West 3000 West 2000 West 1000

Axial System Starting Point for address numbers

Linear Non-Axial System Each street may be numbered starting at a specified location Sometimes similar to State DOT: numbering begins at south or west end, ends at north or east end May simply be defined locally Most often found where there is significant topography, such as mountains, river deltas, other natural features that would make a grid or axial system impractical Useful when streets change directions frequently due to topography or natural barriers

Linear Non-Axial System Starting Point for numbering

Requirements • Creating an address locator • Rules for assigning a location to an address • Reference layer • The address locator assigns addresses based on information in this layer

Using Addresses for Geocoding • A vague method used to describe a location • Addresses are matched against a data reference source that contains address information as well as spatial information (feature geometry)

Addresses • Come in a variety of formats

Address Elements • Pre-modifier: Old North B Street • Pre-directional: North Main Street • Pre-type: Avenue A • Name: Main Street • Post-type: Main Street • Post-directional: Main Street North • Post-modifier: B Street Extended • Separator: Avenue of the Americas

Landmarks A landmark is a named point or area that is prominent enough in the local landscape as to be publicly known • Landmark: Hunter College • Complete Landmark Name: North Building, Hunter College • Community: 123 Urbanization Los Olmos

Geocoding Workflow

Reference Data • Needs to cover the same area as data to be geocoded • Needs to have adequate level of detail • Needs to be current • Needs to be standardized – Use standard abbreviations

Reference Data Source

Address Locators • A dataset that stores the address attributes, associated indexes, and rules that define the process for translating nonspatial descriptions of places, such as street addresses, into spatial features • An address locator contains a snapshot of the reference data used for geocoding, and parameters for standardizing addresses, searching for match locations, and creating output

Address Locators • Contain information including address attributes, indexes, and queries for geocoding • Path to the reference data source and address event table • Algorithms for standardizing address descriptions and matching them to the reference data • Parameters for: – reading address data – matching the address data to the reference data – creating output

Address Locator • Specifies the method to interpret a particular type of address input, relate it with the reference data and deliver a geocoded output • The rule base is a collection of files used to translate the address data into the desired output

Address Locator Properties

Data Organization Reference feature… and it’s associated table • Mapping of attributes

Address (Event) Tables • Any supported tabular format • One field must specify an address

Interactive Matching

Unmatched Records

Recoding Options

Interactive Review Dialog

Interpolating Addresses

Address Data Standards • Existing and Proposed US Standards – FGDC (Federal Geographic Data Committee) - Endorsed, In Use – USPS (U. S. Postal Service) - In Use – NENA (National Emergency Number Association) - Pending adoption