7_Lecture_Geocoding
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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 GIS TUTORIAL 1 - Basic Workbook 2 Lecture 7 GEOCODING OVERVIEW GIS TUTORIAL 1 - Basic Workbook 3 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 GIS TUTORIAL 1 - Basic Workbook 4 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? GIS TUTORIAL 1 - Basic Workbook 5 Geocoding files Tabular data (text or dbase) Street addresses ZIP codes Latitude and longitude GIS TUTORIAL 1 - Basic Workbook 6 Geocoding files Geographic data Street centerlines ZIP code polygons GIS TUTORIAL 1 - Basic Workbook 7 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 GIS TUTORIAL 1 - Basic Workbook 8 Lecture 7 LINEAR (STREET) GEOCODING GIS TUTORIAL 1 - Basic Workbook 9 Linear geocoding (streets) Urban street maps Four street address numbers ranging from low to high for each side of a street segment 100 101 GIS TUTORIAL 1 - Basic Workbook Oak Street 198 199 10 Geocoding steps Original address: 125 East Oak Street 15213 Address parced: |125|East|Oak|Street| 15213 Abbreviations standardized: |125|E|Oak|St|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 #) GIS TUTORIAL 1 - Basic Workbook 11 Geocoding steps Candidates identified: 125 East Oak Street15213 From To Street Type Side Parity Direction Street_ 2 98 Oak St R E W 4344 1 99 Oak St L O W 4345 100 198 Oak St R E E 4346 101 199 Oak St L O E 4357 Candidates scored and filtered: From To Street Type Side Parity Direction Street_ 100 198 Oak St R E E 4346 101 199 Oak St L O E 4357 GIS TUTORIAL 1 - Basic Workbook 12 Geocoding steps Best candidate matched From To Street Type Side Parity Direction Street_ 101 199 Oak St L O E 4357 Oak St 98 100 198 1 99 101 199 Pine Av 2 GIS TUTORIAL 1 - Basic Workbook 123 13 Address components Number 123 Oak St E, Apt. 2, Pittsburgh, PA 15213 Street name 123 Oak St E, Apt. 2, Pittsburgh, PA 15213 Street type 123 Oak St E, Apt. 2, Pittsburgh, PA 15213 Direction, suffix 123 Oak St E, Apt. 2, Pittsburgh, PA 15213 Direction, prefix 123 E Oak St, Apt. 2, Pittsburgh, PA 15213 Unit number 123 Oak St E, Apt. 2, Pittsburgh, PA 15213 Zone, city 123 Oak St E, Apt. 2, Pittsburgh, PA 15213 Zone, ZIP code 123 Oak St E, Apt. 2, Pittsburgh, PA 15213 Items for single number street address: Address 123 Oak St E GIS TUTORIAL 1 - Basic Workbook Unit City ZIP Code Apt. 2 Pittsburgh 15213 14 Lecture 7 PROBLEMS AND SOLUTIONS GIS TUTORIAL 1 - Basic Workbook 15 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 GIS TUTORIAL 1 - Basic Workbook 16 Possible problems Zones 100 Main ST 15101, 100 Main ST 16202 P.O. boxes P.O. Box 125 Missing street (TIGER) information GIS TUTORIAL 1 - Basic Workbook 17 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, fivedigit ZIP code, ZIP+4 extension Use Standard Intersection Connectors &|@ GIS TUTORIAL 1 - Basic Workbook 18 Solutions Use alias tables Alias Address White House 1600 Pennsylvania Avenue Heinz Field 100 Art Rooney Avenue Empire State Building 350 5th Ave Assign house numbers in rural areas Purchase or build high quality maps (field verification) GIS TUTORIAL 1 - Basic Workbook 19 Lecture 7 STREET MAP SOURCES GIS TUTORIAL 1 - Basic Workbook 20 TIGER/Line files 2000 Census street centerlines GIS TUTORIAL 1 - Basic Workbook 21 TIGER/Line files GIS TUTORIAL 1 - Basic Workbook 22 TIGER/Line files GIS TUTORIAL 1 - Basic Workbook 23 Street Map USA GIS TUTORIAL 1 - Basic Workbook 24 GDT Dynamap/2000 U.S. street data Small fee for individual ZIP code layers Map layers are the highest quality streetmap 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 GIS TUTORIAL 1 - Basic Workbook 25 Lecture 7 POLYGON GEOCODING GIS TUTORIAL 1 - Basic Workbook 26 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 GIS TUTORIAL 1 - Basic Workbook 27 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 GIS TUTORIAL 1 - Basic Workbook 28 Polygon geocoding (ZIP codes) GIS TUTORIAL 1 - Basic Workbook 29 Polygon geocoding (ZIP codes) Points created at ZIP code centroids GIS TUTORIAL 1 - Basic Workbook 30 Polygon geocoding (ZIP codes) Spatially join points to polygons to make choropleth map GIS TUTORIAL 1 - Basic Workbook 31 Choropleth map result GIS TUTORIAL 1 - Basic Workbook 32 Lecture 7 GEOCODING IN ARCCATALOG GIS TUTORIAL 1 - Basic Workbook 33 Create address locator ArcCatalog GIS TUTORIAL 1 - Basic Workbook 34 Choose address locator style Skeleton of the address locator Based on data tables and reference layer GIS TUTORIAL 1 - Basic Workbook 35 Choose reference layer Streets, ZIP codes GIS TUTORIAL 1 - Basic Workbook 36 Address locator properties GIS TUTORIAL 1 - Basic Workbook 37 Geocode in ArcMap Add tabular data and streets layer Add address locator Geocode addresses View geocoding results Interactively rematch addresses GIS TUTORIAL 1 - Basic Workbook 38 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 GIS TUTORIAL 1 - Basic Workbook 39 Prepare log file Log file includes reasons why addresses did not geocode Useful for future work on cleaning addresses or repairing street maps Incorrect address Possible reason/solution 490 Penn Avenue Missing ZIP code 111 Hawksworth Spelled incorrectly 900 Smallman Street TIGER street missing 900 Lib Ave Spelled incorrectly GIS TUTORIAL 1 - Basic Workbook 40 Lecture 7 USEFUL WEBSITES GIS TUTORIAL 1 - Basic Workbook 41 Useful Web sites http://www.usps.gov/ http://www.geocode.com/geocode.htm http://www.batchgeocode.com/ http://www.mapquest.com http://maps.google.com http://www.zipinfo.com http://zipskinny.com/ http://www.semaphorecorp.com/cgi/zp4.html GIS TUTORIAL 1 - Basic Workbook 42 Summary Geocoding overview Linear (street) geocoding Problems and solutions Street map sources Polygon geocoding Geocoding in ArcView Useful Web sites GIS TUTORIAL 1 - Basic Workbook 43
