GIS Tutorial 1 Lecture 7 Geocoding

Outline  Geocoding overview  Linear (street) geocoding  Problems and solutions  Street map sources  Polygon geocoding  Geocoding in ArcCatalog & ArcMap  Useful Web sites 2 GIS TUTORIAL 1 - Basic Workbook

GEOCODING OVERVIEW Lecture 7 3 GIS TUTORIAL 1 - Basic Workbook

Geocoding  Process of creating geometric representations for locations (e.g., points) from descriptions of locations (e.g., street addresses)  Uses a computer program that employs code tables to standardize address components called a geocoding engine  Two ways to geocode  Batch geocoding—attempts to match all addresses  Interactive rematching—sophisticated user interface to match addresses 4 GIS TUTORIAL 1 - Basic Workbook

Geocoding examples  City’s economic development department maps technology businesses by street addresses to see technology-rich areas in a city  County health director maps personal care and nursing homes and compares them to elderly population by neighborhood  Business maps store locations and compares to competitor locations  Emergency dispatch operators geocode an address to determine who should respond to an emergency call  Others? 5 GIS TUTORIAL 1 - Basic Workbook

Geocoding files  Tabular data (text or dbase)  Street addresses  ZIP codes  Latitude and longitude 6 GIS TUTORIAL 1 - Basic Workbook

Geocoding files  Geographic data  Street centerlines  ZIP code polygons 7 GIS TUTORIAL 1 - Basic Workbook

Other geocoding files  Lines  Railroads, rivers  Polylines  Parcels, census blocks, tracts, MCD/CCDs, places, counties, etc.  Points  Landmarks such as churches, schools, and other cultural features represented as TIGER as points 8 GIS TUTORIAL 1 - Basic Workbook

LINEAR (STREET) GEOCODING Lecture 7 9 GIS TUTORIAL 1 - Basic Workbook

Linear geocoding (streets)  Urban street maps  Four street address numbers ranging from low to high for each side of a street segment Oak Street 10 GIS TUTORIAL 1 - Basic Workbook

Geocoding steps Original address: 125 East Oak Street Address parced: |125|East|Oak|Street| Abbreviations standardized: |125|E|Oak|St|15213 Elements assigned to match keys: [HN]:125 [SN]:Oak[ST]:St [SD]:E [ZP]:15213 Elements assigned to match keys: [HN]:125 [SN]:Oak[ST]:St [SD]:E [ZP]:15213 Index values calculated: [HN]:125 [SN]:Oak(Soundex # ) [ST]:St [SD]:E [ZP]:15213 (Index #) 11 GIS TUTORIAL 1 - Basic Workbook

Geocoding steps FromToStreetTypeSideParityDirectionStreet_ 298OakStREW OakStLOW OakStREE OakStLOE4357 Candidates identified: 125 East Oak Street15213 Candidates scored and filtered: FromToStreetTypeSideParityDirectionStreet_ OakStREE OakStLOE GIS TUTORIAL 1 - Basic Workbook

Geocoding steps FromToStreetTypeSideParityDirectionStreet_ OakStLOE4357 Best candidate matched Oak St Pine Av GIS TUTORIAL 1 - Basic Workbook

Number123 Oak St E, Apt. 2, Pittsburgh, PA Street name 123 Oak St E, Apt. 2, Pittsburgh, PA Street type 123 Oak St E, Apt. 2, Pittsburgh, PA Direction, suffix123 Oak St E, Apt. 2, Pittsburgh, PA Direction, prefix 123 E Oak St, Apt. 2, Pittsburgh, PA Unit number123 Oak St E, Apt. 2, Pittsburgh, PA Zone, city123 Oak St E, Apt. 2, Pittsburgh, PA Zone, ZIP code123 Oak St E, Apt. 2, Pittsburgh, PA Items for single number street address: Address Unit City ZIP Code 123 Oak St E Apt. 2 Pittsburgh Address components 14 GIS TUTORIAL 1 - Basic Workbook

PROBLEMS AND SOLUTIONS Lecture 7 15 GIS TUTORIAL 1 - Basic Workbook

Possible problems  Variations in street names  Fifth Avenue, Fifth Ave., 5th AV  Saw Mill Run Blvd, Route 51  Data entry errors  Fidth Avenue  Sawmill Run  Place Names  White House, Heinz Field, Empire State Building  Intersections  Fifth Avenue and Craig Street 16 GIS TUTORIAL 1 - Basic Workbook

Possible problems  Zones  100 Main ST 15101, 100 Main ST  P.O. boxes  P.O. Box 125  Missing street (TIGER) information 17 GIS TUTORIAL 1 - Basic Workbook

Solutions  Clean data before geocoding  Use postal address standards  Publication 28 of the U.S. Post Office (2000)  Ultimate source on mailing address formats and codes  Provides standard street address formats  Standards include house number, prefix directional, street name, street suffix, common unit designator abbreviation for apartment, city, state abbreviation, five- digit ZIP code, ZIP+4 extension  Use Standard Intersection Connectors  & 18 GIS TUTORIAL 1 - Basic Workbook

Solutions  Use alias tables  Assign house numbers in rural areas  Purchase or build high quality maps (field verification) 19 GIS TUTORIAL 1 - Basic Workbook AliasAddress White House1600 Pennsylvania Avenue Heinz Field100 Art Rooney Avenue Empire State Building350 5th Ave

STREET MAP SOURCES Lecture 7 20 GIS TUTORIAL 1 - Basic Workbook

TIGER/Line files  2000 Census street centerlines 21 GIS TUTORIAL 1 - Basic Workbook

TIGER/Line files 22 GIS TUTORIAL 1 - Basic Workbook

TIGER/Line files 23 GIS TUTORIAL 1 - Basic Workbook

Street Map USA 24 GIS TUTORIAL 1 - Basic Workbook

GDT Dynamap/2000 U.S. street data  Small fee for individual ZIP code layers  Map layers are the highest quality street- map layers in terms of appearance, completeness, and accuracy  Maps include more than 14 million U.S. street segments and include postal boundaries, landmarks, water features, and other features 25 GIS TUTORIAL 1 - Basic Workbook

POLYGON GEOCODING Lecture 7 26 GIS TUTORIAL 1 - Basic Workbook

Polygon geocoding  Method to map data whose identifier is a polygon (e.g. ZIP code, city, parcel identifier- ppn, or county)  Create an aggregate table with a single record for each unique polygon  Count the records for each polygon  Join table to corresponding polygon layer  Symbolize with a choropleth map or graduated point symbols 27 GIS TUTORIAL 1 - Basic Workbook

TIGER: Polygon topology  ZIP codes  American Indian Reservation  Alaska Nature Village Statistical Area  Tribal Designated Statistical Area  Tribal Jurisdiction Statistical Area  Alaska Nature Regional Corp.  FIPS State and County Codes  MCD  Place  Census tract/block groups/blocks 28 GIS TUTORIAL 1 - Basic Workbook

Polygon geocoding (ZIP codes) 29 GIS TUTORIAL 1 - Basic Workbook

Polygon geocoding (ZIP codes)  Points created at ZIP code centroids 30 GIS TUTORIAL 1 - Basic Workbook

Polygon geocoding (ZIP codes)  Spatially join points to polygons to make choropleth map 31 GIS TUTORIAL 1 - Basic Workbook

Choropleth map result 32 GIS TUTORIAL 1 - Basic Workbook

GEOCODING IN ARCCATALOG Lecture 7 33 GIS TUTORIAL 1 - Basic Workbook

Create address locator  ArcCatalog 34 GIS TUTORIAL 1 - Basic Workbook

Choose address locator style  Skeleton of the address locator  Based on data tables and reference layer 35 GIS TUTORIAL 1 - Basic Workbook

Choose reference layer  Streets, ZIP codes GIS TUTORIAL 1 - Basic Workbook 36

Address locator properties 37 GIS TUTORIAL 1 - Basic Workbook

Geocode in ArcMap  Add tabular data and streets layer  Add address locator  Geocode addresses  View geocoding results  Interactively rematch addresses 38 GIS TUTORIAL 1 - Basic Workbook

Address rematching  Investigate unmatched addresses  Generally requires expertise with knowledge of local streets  Compare street name in the attributes of streets table and address table 39 GIS TUTORIAL 1 - Basic Workbook

Prepare log file  Log file includes reasons why addresses did not geocode  Useful for future work on cleaning addresses or repairing street maps 40 GIS TUTORIAL 1 - Basic Workbook Incorrect addressPossible reason/solution 490 Penn AvenueMissing ZIP code 111 HawksworthSpelled incorrectly 900 Smallman StreetTIGER street missing 900 Lib AveSpelled incorrectly

USEFUL WEBSITES Lecture 7 41 GIS TUTORIAL 1 - Basic Workbook

Useful Web sites         42 GIS TUTORIAL 1 - Basic Workbook

Summary  Geocoding overview  Linear (street) geocoding  Problems and solutions  Street map sources  Polygon geocoding  Geocoding in ArcView  Useful Web sites 43 GIS TUTORIAL 1 - Basic Workbook