gis tutorial 1 lecture 7 geocoding. outline geocoding overview linear (street) geocoding problems...

GIS Tutorial 1

Lecture 7Geocoding

Outline Geocoding overview Linear (street) geocoding Problems and solutions Street map sources Polygon geocoding Geocoding in ArcCatalog & ArcMap Useful Web sites

2GIS TUTORIAL 1 - Basic Workbook

GEOCODING OVERVIEWLecture 7


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


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?


Geocoding files Tabular data (text or dbase)

Street addresses ZIP codes Latitude and longitude


Geocoding files Geographic data

Street centerlines ZIP code polygons


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


LINEAR (STREET) GEOCODING

Lecture 7


Linear geocoding (streets) Urban street maps

Four street address numbers ranging from low to high for each side of a street segment

100 198

101 199

Oak Street


Geocoding steps

Original address: 125 East Oak Street 15213Original address: 125 East Oak Street 15213

Address parced: |125|East|Oak|Street| 15213Address parced: |125|East|Oak|Street| 15213

Abbreviations standardized: |125|E|Oak|St|15213Abbreviations standardized: |125|E|Oak|St|15213

Elements assigned to match keys:[HN]:125 [SN]:Oak[ST]:St [SD]:E [ZP]:15213Elements 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 #)Index values calculated: [HN]:125 [SN]:Oak(Soundex # ) [ST]:St [SD]:E [ZP]:15213 (Index #)


Geocoding steps

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 identified: 125 East Oak Street15213Candidates identified: 125 East Oak Street15213

Candidates scored and filtered:Candidates scored and filtered:


Street_

100 198 Oak St R E E 4346

101 199 Oak St L O E 4357


Geocoding steps


Street_

101 199 Oak St L O E 4357

Best candidate matchedBest candidate matched

Oak StPin

e A

v100

101

198

199123

2

1

98

99


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 Unit City ZIP Code 123 Oak St E Apt. 2 Pittsburgh 15213

Address components


PROBLEMS AND SOLUTIONSLecture 7


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


Possible problems Zones

100 Main ST 15101, 100 Main ST 16202

P.O. boxes P.O. Box 125

Missing street (TIGER) information


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

& | @


Solutions

Use alias tables

Assign house numbers in rural areas Purchase or build high quality maps (field

verification)


Alias Address

White House 1600 Pennsylvania Avenue

Heinz Field 100 Art Rooney Avenue

Empire State Building 350 5th Ave

STREET MAP SOURCESLecture 7


TIGER/Line files

2000 Census street centerlines


TIGER/Line files


Street Map USA


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


POLYGON GEOCODINGLecture 7


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


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


Polygon geocoding (ZIP codes)


Polygon geocoding (ZIP codes)

Points created at ZIP code centroids


Polygon geocoding (ZIP codes) Spatially join points to polygons to

make choropleth map


Choropleth map result


GEOCODING IN ARCCATALOGLecture 7


Create address locator ArcCatalog


Choose address locator style Skeleton of the address locator Based on data tables and reference

layer


Choose reference layer

Streets, ZIP codes

GIS TUTORIAL 1 - Basic Workbook 36

Address locator properties


Geocode in ArcMap

Add tabular data and streets layer

Add address locator

Geocode addresses

View geocoding results

Interactively rematch addresses


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


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

USEFUL WEBSITESLecture 7


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


Summary Geocoding overview Linear (street) geocoding Problems and solutions Street map sources Polygon geocoding Geocoding in ArcView Useful Web sites


gis tutorial 1 lecture 7 geocoding. outline geocoding overview linear (street) geocoding problems...

Documents

geocoding slide

gis tutorial

basic workbook slide

geocoding process

geocoding engine

e oak st

street type

street segment