The Black Art of GeocodingFinding that elusive lat/lon

John Fagan, Microsoft

The Black Art of Geocoding

Finding that elusive lat/lon

John FaganProgram Manager

Microsoft Corporation

@johnbfagan

We been making maps for 1000’s of years

Well known and established standards/principles

Lots of experience in building software to create bitmaps from vector and raster data

Data availability & Simple data model

Mapping easy to scale

...and so is routing

1000’s years experience in wayfindingOver 50 years experience in routing algorithmsDijkstra's shortest path algorithm (1959)

Data availability & Simple data model

Routing, easy to scale

Geocoding not so easy

20 years experience10 years of global Geocoding5 years exposing geocoding to the mass consumer

No standard algorithmsVery few databases purpose built (maybe GNAF)Very hard to scale

Geocoding is fundamental

Cant get a map without a geocodeCant get a route without a geocodeCant view your data without a geocode80% of all information contains a geographic element.

It used to be easier

Now its hard

User expectations change with unstructured input

67 hill veiw road, s61 2bn in the 1850's1.5 hours from Niceexact directions from Bangkok Patana School to Suvanapumi Airport in Bangkok.10 mile radius from se20 7uahow long would it take me to walk around cancunhow to get to m13 gb from g83 9le by cardo bearded dragons bite?

But ......Geocoding NOT about Search

52.19157,-1.70415

The reason it's called 'I'm Feeling Lucky,' is of course that's a pretty damn ambitious goal. I mean to get the exact right one thing without even giving you a list of choices, and so you have to feel a little bit lucky if you're going to try that with one go," tried to explain Sergey Brin.

Why is it hard (2 reasons)

Parsing: Hard to understand unstructured input

Finding Stratford-upon-Avon

stratfordstratford upon avonStratford upon havenStratfordUponAvonStratford-Upon-Avonstratford on avon stratford-on-avonstratford 0n avonstratford - upon-avon stratford on avaonstratford apon avonstratford upon aavonstratford uppon avon

Finding Stratford-upon-Avon

Parsing

In computer science and linguistics, parsing, or, more formally, syntactic analysis, is the process of analyzing a text, made of a sequence of tokens (for example, words), to determine its grammatical structure with respect to a given (more or less) formal grammar.

http://en.wikipedia.org/wiki/Parsing

Old way of Parsing – Rules based

A rules based approach (mainly done with regular expressions)

Probabilistic approach

Machine learnedRequires you to “train” the engineRequires truth sets of training data

http://en.wikipedia.org/wiki/Hidden_Markov_model

Probabilistic approach: Hidden Markov Model

input --> 165 fleet street london EC4A 2DY

output --> address {

street number : 165street : fleet street city : london postcode : EC4A 2DY }

Multimap stats

grammar % share

Postcode 67.9

Locality 14.8

Landmark 3.3

Street name 3

Street name, Localiry 2.4

street number street name 0.5

County 0.5street number street name locality 0.5

Locality county 0.4

Parsing has its limitations

Parsing failuresMultimap/Bing Maps (st andrews scotland)Google (uk near Boston, MA, USA)All fail - House number plus postcode (165, EC4A 2DY)

Parsing using a Spatial Engine

http://research.microsoft.com/en-us/people/josephj/acm_gis_2007_robust_location_search.pdf

Why is it hard (Data)

Hard to match input with reference database

[OSM-talk] Baghdad mapsI am informed that any road may have up to 4 names (which may be the same or different):

1) The pre-Saddam name 2) The Saddam-era name. 3) The "public" name - What the people who live there call it. 4) The "Official" name - What the new Government calls it.

This situation is further complicated by language and social issues: Language

5) The roads are names in Arabic.6) There is no fixed translation between the Arabic and Latin alphabets.

Social Issues:

1) Sunnis tend to use the Saddam-era names 7) Shia tend to rename streets and won't acknowledge Saddam-era names. 8) Ethnic cleansing is changing the neighbourhoods and hence the names. 9) Names (such as 14th July Bridge) will change later.

My translator's opinion is that street names are going to take at least 2-3 years to settle down.

http://lists.openstreetmap.org/pipermail/talk/2007-February/011273.html

Don't throw away your data

Multimap have always kept old postcodes10% of Multimap’s postcode database is of “dead” postcodesThis might not work for routing and mapping, but very valuable for Geocoding

EC4A 1HE – Postcode of vintage 2002

Lash data and enrich

Stratford-upon-Avon

Future = Real time Geocoding?

Summary

Mapping and Routing – FIXEDGeocoding – Must Try HarderParsing Data

thanks

john fagan

ubergeo.com

@johnbfagan