The following technical report details of the inner workings of the USC WebGIS Geocoding Platform: Goldberg, D.W., 2009. The USC WebGIS Open Source Geocoding Platform. Technical Report No 11. Los Angeles CA: University of Southern California GIS Research Laboratory. Available online at: http://gislab.usc.edu/i/publications/gislabtr11.pdf.
The USC Geocoding Platform currently supports US geocoding
2008 US Census Bureau TIGER/Line Files Edges Places Cities Consolidated Cities Zip Code Tabulation Area (ZCTA) County Sub Regions Counties States 2005 US Census Bureau TIGER/Line Files Edges 2000 US Census Bureau Catographic Boundary Files Places Cities Zip Code Tabulation Area (ZCTA) Counties Los Angeles County Assessor’s Parcel Files USPS Tiger/ZIP + 4 Files If you have other reference data sets you would like to use for and/or contribute to the geocoding process on this site, we can incorporate them. Please contact us for more information.
Deterministic Matching This version of the USC geocoder performs strictly deterministic matching, i.e., probabilistic matching is not attempted. This means that if an exact match is not found in a particular reference dataset, no match is returned for that reference data layer. Attribute Relaxation This option directs the geocoder to try alternative versions of the input data in the case when an exact match can not be found. In particular, attributes of the input address are removed from the query, first one at a time and then in combination with each other. Attribute relaxation is performed (if the option is selected) on the following address attributes: Rank Attribute 1)Street predirectional 2)Street postdirectional 3)Street suffix 4)City 5)Zip An example of the first few iterations it will try are listed in the next table: Number Pre Name Suffix Post Zip City State 3620SVermontAveN90089Los AngelesCa 3620 VermontAveN90089Los AngelesCa 3620SVermontAve 90089Los AngelesCa 3620SVermont N90089Los AngelesCa 3620 VermontAve 90089Los AngelesCa 3620 Vermont N90089Los AngelesCa 3620SVermont 90089Los AngelesCa 3620 Vermont 90089Los AngelesCa Substring Matching This option directs the geocoder to use substring matching techniques to test for matches in the database. Using this approach increases the likelyhood of finding a match if the input data or reference data are incomplete (the recall is increased). However, using this also increases the chances that wrong results are returned (the precision is descreased). The following table shows examples of this strategy: Query Reference Feature Match Vermont Vermont yes Verm Vermont yes Mont Vermont yes Soundex Matching This option directs the geocoder to use soundex matching techniques to test for matches in the database. Using this approach increases the likelyhood of finding a match if the input data or reference data have minor misspellings (the recall is increased). However, using this also increases the chances that wrong results are returned (the precision is descreased). The following table shows examples of this strategy: Query Query Soundex Reference Feature Reference Feature Soundex Match Vermont V655 Vermont V655 yes Vermond V655 Vermont V655 yes Varnend V655 Vermont V655 yes
Linear Interpolation The following linear interpolation techniques are used: 1) Address range interpolation 2) Uniform lot interpolation The following areal-unit interpolation techniques are used: 1) Geometric centroid Full list of API Output InterpolationType Values Unknown LinearInterpolation ArealInterpolation None NotAttempted Full list of API Output InterpolationSubType Values Unknown LinearInterpolationAddressRange LinearInterpolationUniformLot LinearInterpolationActualLot LinearInterpolationMidPoint ArealInterpolationBoundingBoxCentroid ArealInterpolationConvexHullCentroid ArealInterpolationGeometricCentroid None NotAttempted
1) Address range interpolation 2) Uniform lot interpolation
1) Geometric centroid
Parcel centroid A exact match was found to a parcel and its centroid is returned as output Street segment A match was found to the street segment and the address range associated with the segment was used to interpolate a point to return as output ZCTA A match was found to the ZIP portion of the address and its centroid was returned as output City A match was found to the city portion of the address and its centroid was returned as output County subregion A match was found to the city portion of the address in the county subregion reference data set and its centroid was returned as output County A match was found to the city portion of the address in the county reference data set and its centroid was returned as output Unmatchable A match could not be found for the input Full list of API Output MatchingGeographyTypes Values Unknown GPS BuildingCentroid BuildingDoor Parcel StreetSegment StreetIntersection StreetCentroid USPSZipPlus5 USPSZipPlus4 USPSZipPlus3 USPSZipPlus2 USPSZipPlus1 USPSZip ZCTAPlus5 ZCTAPlus4 ZCTAPlus3 ZCTAPlus2 ZCTAPlus1 ZCTA City ConsolidatedCity MinorCivilDivision CountySubRegion County State Country Unmatchable
Exact parcel centroid A exact match was found to a parcel and its centroid is returned as output Nearest parcel centroid A match was found to the nearest parcel and its centroid is returned as output Uniform lot interpolation A match was found to the street segment and the number of lots on the segment was used to interpolate a point to return as output Address range interpolation A match was found to the street segment and the address range associated with the segment was used to interpolate a point to return as output ZCTA centroid A match was found to the ZIP portion of the address and its centroid was returned as output City centroid A match was found to the city portion of the address and its centroid was returned as output County subregion centroid A match was found to the city portion of the address in the county subregion reference data set and its centroid was returned as output County centroid A match was found to the city portion of the address in the county reference data set and its centroid was returned as output Unmatchable A match could not be found for the input Full list of API Output GeocodeQualityType Values Unknown GPS BuildingFrontDoor BuildingCentroid ExactParcelCentroidPoint ExactParcelCentroid NearestParcelCentroidPoint NearestParcelCentroid ActualLotInterpolation UniformLotInterpolation AddressRangeInterpolation StreetIntersection StreetCentroid ZCTAPlus5Centroid ZCTAPlus4Centroid ZCTAPlus3Centroid ZCTAPlus2Centroid ZCTAPlus1Centroid ZCTACentroid USPSZipPlus5LineCentroid USPSZipPlus4LineCentroid USPSZipPlus5AreaCentroid USPSZipPlus4AreaCentroid USPSZipPlus3AreaCentroid USPSZipPlus2AreaCentroid USPSZipPlus1AreaCentroid USPSZipAreaCentroid CityCentroid ConsolidatedCityCentroid CountySubdivisionCentroid CountyCentroid StateCentroid CountryCentroid DynamicFeatureCompositionCentroid Unmatchable
Exact parcel centroid Nearest parcel centroid Uniform lot interpolation Address range interpolation ZIP code centroid City centroid County subdivision centroid County centroid State centroid Country centroid
Group Code Value Code Name Success200Success API Key Errors400API Key Error API Key Errors401API Key Missing API Key Errors402API Key Invalid API Key Errors403API Key Not Activated Non-Profit Errors450Non Profit Error Non-Profit Errors451Non Profit Not Confirmed Quota Errors470Quota Exceeded Error Quota Errors471Anonymous Quota Exceeded Quota Errors472Paid Quota Exceeded Versions Errors480Version Missing Versions Errors481Version Invalid Internal Errors500Failure Internal Errors501Internal Error Unknown Errors0Unknown
StreetAddress The matched input data was a postal street address Example: 3620 South Vermont Ave, Los Angeles, CA 90089-0255 PostOfficeBox The matched input data was a Post Office Box address Example: PO Box 0255, Los Angeles, CA 90089-0255 RuralRoute The matched input data was a Rural Route address Example: RR 13 Box 2, Los Angeles, CA 90089-0255 StarRoute The matched input data was a Star Route address Example: Star Route 13 Box 2, Los Angeles, CA 90089-0255 HighwayContractRoute The matched input data was a Highway Contract Route address Example: HC 13 Box 2, Los Angeles, CA 90089-0255 Intersection The matched input data was an intersection of two or more streets Example: 36th and Vermont, Los Angeles, CA NamedPlace The matched input data was a named place Example: USC GIS Research Laboratory, Los Angeles, CA RelativeDirection The matched input data was a relative direction Example: 1 mile south of downtown Los Angeles Unmatchable A match could not be found for the input Full list of API Output MatchedLocationTypes Values Unknown StreetAddress PostOfficeBox RuralRoute StarRoute HighwayContractRoute Intersection NamedPlace RelativeDirection Unmatchable
Example: 3620 South Vermont Ave, Los Angeles, CA 90089-0255
Example: PO Box 0255, Los Angeles, CA 90089-0255
Example: RR 13 Box 2, Los Angeles, CA 90089-0255
Example: Star Route 13 Box 2, Los Angeles, CA 90089-0255
Example: HC 13 Box 2, Los Angeles, CA 90089-0255
Example: 36th and Vermont, Los Angeles, CA
Example: USC GIS Research Laboratory, Los Angeles, CA
Example: 1 mile south of downtown Los Angeles
Exact The input data exactly matched a feature in the reference data source: input 3620 S Vermont Ave, Los Angeles, CA 90089-0255 reference 3620 S Vermont Ave, Los Angeles, CA 90089-0255 Relaxed One or more of the input data attributes had to be removed to find a match in the reference data source: input 3620 Vermont Ave, Los Angeles, CA 90089-0255 reference 3620 S Vermont Ave, Los Angeles, CA 90089-0255 - South is missing from input and is present in the reference For more details, see the section on Address Relaxation above. Soundex One or more of the input data attributes had to be matched with soundex to find a match in the reference data source: input 3620 S Vermonnt Ave, Los Angeles, CA 90089-0255 reference 3620 S Vermont Ave, Los Angeles, CA 90089-0255 - Soundex("Vermonnt") = V655 = Soundex("Vermont") For more details, see the section on Soundex Matching above. Full list of API Output FeatureMatchTypes Values NoMatch Exact Relaxed Substring Soundex Composite Unknown
input 3620 S Vermont Ave, Los Angeles, CA 90089-0255 reference 3620 S Vermont Ave, Los Angeles, CA 90089-0255
input 3620 Vermont Ave, Los Angeles, CA 90089-0255 reference 3620 S Vermont Ave, Los Angeles, CA 90089-0255 - South is missing from input and is present in the reference
input 3620 S Vermonnt Ave, Los Angeles, CA 90089-0255 reference 3620 S Vermont Ave, Los Angeles, CA 90089-0255 - Soundex("Vermonnt") = V655 = Soundex("Vermont")
Success A exact match was found Unmatchable A match could not be found for the input Full list of API Output FeatureMatchingResultTypes Values Unknown Success Ambigous Composite LessThanMinimumScore InvalidFeature NullFeature Unmatchable ExceptionOccurred
ID Type Description 1 Input data Street intersection data are not supported 2 Feature matching A state is required to obtain any type of street- or parcel-level match 3 Feature matching Probabalistic feature matching is not supported 4 Feature matching/Feature interpolation Street centroids are not returned for street level matches without address numbers 5 Address parsing/Feature matching Zip codes with leading zero's get the leading zero's removed 6 Address parsing/Feature matching City portions of an address are not normalized so you should pre-normalize them if possible, e.g., use "East Hanover" instead of "E Hanover"
