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Rethinking Geocoding In Utah


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Presentation given to Utah Geographic Information Council (UGIC) annual conference April 6, 2011.

Presentation focuses on alternative strategies to traditional GIS geocoding that may be employed for web service context to locate addresses in Utah.

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Rethinking Geocoding In Utah

  1. 1. Rethinking Geocoding Bert Granberg AGRC
  2. 2. Paradigm shift <ul><li>2000: </li></ul><ul><ul><li>Geocoding Addresses was cool... </li></ul></ul><ul><ul><ul><li>“ Wow, it found it!” </li></ul></ul></ul><ul><li>2010: </li></ul><ul><ul><li>Accurately Locating Addresses is critical </li></ul></ul><ul><ul><ul><li>“ Every address must match!” </li></ul></ul></ul>
  3. 4. Basic GIS Locator & Process <ul><li>Input: Structured Address(es) </li></ul><ul><li>Output: Match Candidates and Scores </li></ul><ul><li>Familiar but soooo dated </li></ul><ul><li>Many shortcomings: </li></ul><ul><ul><li>Input Address Data </li></ul></ul><ul><ul><ul><li>Un-standardized input addresses </li></ul></ul></ul><ul><ul><ul><li>Incorrect zones (zip codes in particular) </li></ul></ul></ul><ul><ul><li>Imperfect Address Source Data </li></ul></ul><ul><ul><ul><li>Imperfect zone information </li></ul></ul></ul><ul><ul><ul><li>Prefix direction used inconsistently…USPS standard in conflict with local address vernacular </li></ul></ul></ul>
  4. 5. Shortcomings (cont.) <ul><ul><li>Process Too Simple </li></ul></ul><ul><ul><ul><li>Single address source dataset (centerlines) </li></ul></ul></ul><ul><ul><ul><li>Single search strategy (indexing) ….composite and custom locators allow more complex logic </li></ul></ul></ul><ul><ul><ul><li>Focus on HN + StreetName addresses, what about route/milepost or non-addressed locations </li></ul></ul></ul><ul><ul><ul><li>User expectation for more flexible, simple input interface (google)??? </li></ul></ul></ul><ul><ul><li>Output </li></ul></ul><ul><ul><ul><li>QCing of results done rarely </li></ul></ul></ul><ul><ul><ul><li>Improvements to data and process not easily shared </li></ul></ul></ul><ul><ul><ul><li>Historical addresses are next to impossible to find </li></ul></ul></ul><ul><ul><ul><li>Range-based, interpolated point may not even be on the property </li></ul></ul></ul><ul><ul><ul><li>Address point may not be at preferred location (centroid, frontage, building, doorstep, driveway, gate) </li></ul></ul></ul><ul><ul><li>Overall All </li></ul></ul><ul><ul><ul><li>Different users get imperfect, inconsistent results </li></ul></ul></ul>
  5. 6. Geocoding at AGRC <ul><li>“ Local data is better data” </li></ul><ul><li>“ Open, public domain data makes sense” </li></ul><ul><ul><li>Cost </li></ul></ul><ul><ul><li>Control </li></ul></ul><ul><ul><li>Currency </li></ul></ul>
  6. 7. Utah Registered Voter Geocoding Rate By County, May 2010 Overall Match Rate, Weighted By Population = 95% 0% 80% 60% 40% 20% 100%
  7. 8. Geocoding at AGRC (cont.) <ul><li>Web service based </li></ul><ul><li>Address, Zone (2 parameters) </li></ul><ul><li>3 levels of aliasing (composite address locator) </li></ul><ul><li>95% match statewide (range from 47-98% by county) VISTA database </li></ul><ul><li>Can use zip or incorporated city for “zone” </li></ul>
  8. 9. GC Web Service
  9. 10. Commitments Made: <ul><li>911 Committee Goals </li></ul><ul><ul><li>95% Address Match Rate by June 2011 </li></ul></ul><ul><ul><li>Statewide Address Points June 2012 </li></ul></ul><ul><li>VISTA, Elections Management </li></ul><ul><ul><li>GIS Precinct Assignment and Counts </li></ul></ul><ul><li>Broadband Project funded Address Point project </li></ul><ul><ul><li>1-2 year time frame for building sustainable processes </li></ul></ul><ul><ul><li>Collect Once application </li></ul></ul>
  10. 11. In progress <ul><li>Developing Address Point-based location services </li></ul><ul><ul><li>Parcel to Address Polygon to Address Point 'Starting Point' script </li></ul></ul><ul><ul><li>Proposed address point data model </li></ul></ul><ul><li>Street Centerline </li></ul><ul><ul><li>Incorporate 'address system' as an attribute for potential zone use </li></ul></ul><ul><ul><li>Prefix and suffix direction issues </li></ul></ul><ul><li>Developing advanced input address handling logic </li></ul><ul><li>Developing advanced address location logic </li></ul><ul><ul><li>Different classes of addresses get handed to different location service </li></ul></ul><ul><li>Functionality to gather improvement data from batch and web app results and pass along to data stewards </li></ul><ul><li>Magic search box beginning to take shape </li></ul><ul><li>New generation, distributed data sharing portal, planning phases </li></ul>
  11. 12. Address Starting Points from parcels
  12. 13. Magic Zoom
  13. 14. Input Address Classes <ul><li>_HN _AlpName (123 Main) </li></ul><ul><li>_HN _Pre _AlpName (123 S Main) </li></ul><ul><li>_HN _Pre _ AlpName _ Type + Zone (123 S Main St) </li></ul><ul><li>_HN _AlpName _ Type + Zone (123 Main St) </li></ul><ul><li>_HN _Pre _NumName _Suf + Zone (123 S 300 E) </li></ul><ul><li>_Name _IntSep _Name + Zone (Main St and 600 S) </li></ul><ul><li>_Milepost + _Route (123.456 NB I-15) </li></ul><ul><li>_GeogName ( Delicate Arch) </li></ul><ul><li>_GeogName + Zone (Riverwoods Conference Center, Logan ) </li></ul><ul><li>Where Zone = {Zip, City, AddressSystem} </li></ul>
  14. 15. Advanced Match Logic Sketch <ul><li>With Input Address: </li></ul><ul><li>Is Geographic Place? </li></ul><ul><li>Is Milepost & Route? </li></ul><ul><li>Is Intersection? </li></ul><ul><li>Is Numeric Street Type? </li></ul><ul><li>Has Prefix Direction? </li></ul><ul><ul><li>Lookup and use Address System Zone from supplied zip/city </li></ul></ul><ul><ul><li>Use Prefix enabled locators </li></ul></ul><ul><li>Has No Prefix Direction, Prefix Not Critical for Streetname Within Zone? </li></ul><ul><ul><li>Lookup and use Address System Zone from supplied zip/city </li></ul></ul><ul><ul><li>Use Prefix disabled locators </li></ul></ul><ul><li>Has No Prefix Direction, Prefix Is Critical For StreetName Within Zone? </li></ul><ul><ul><li>Use supplied Zip/City Zone </li></ul></ul><ul><ul><li>Use Prefix disabled locators </li></ul></ul><ul><ul><li>Guess best match? </li></ul></ul><ul><ul><li>Return match note that prefix should be used </li></ul></ul>
  15. 16. Other, future considerations <ul><li>Interim study on Address Quality in government databases (every address locatable?) </li></ul><ul><li>Centralized Repository & Services </li></ul><ul><li>Quality Assessment feedback loop </li></ul><ul><li>Utah Addressing Board??? </li></ul><ul><li>Non-Public Sector Services </li></ul><ul><ul><li>Commercial ?? </li></ul></ul><ul><ul><li>Open APIs ?? </li></ul></ul>
  16. 17. Comments, Questions? <ul><li>Bert Granberg </li></ul><ul><ul><li>[email_address] </li></ul></ul><ul><ul><li>@BertAGRC </li></ul></ul>