Geocoding Software from SGSI
  Geocoding Software
Featuring MapMarker® Plus from MapInfo



Geocoding:  A practical definition 
The process of placing data on a map. 

Before geocoding

Name Address Zip
Bill Smith 123 Orca St 98000

After geocoding

Geocoding:  A technical definition

  • The process of matching records in two databases: your address database (without map position information) and a reference street map or other "address dictionary".

  • Geocoding software (e.g., MapInfo Pro or MapMarker) links records in the two databases by matching street names and address numbers:  e.g., matches the street name in the address to a street name in the street map etc.

  • When your database records are successfully linked or matched to a reference street map database, your records are tagged with the correct map positions, typically lat-lon coordinates.

  • Thereafter, your data table carries its own position information and can be mapped without using the reference  street map or address dictionary.

  • MapInfo Pro, by default, hides the map coordinates:  i.e., it does not list the Lat-Lon values in the tables. But it uses the coordinates, nevertheless, behind the scenes.

Before geocoding

Name Address Zip XCoord YCoord
Bill Smith 123 Orca St 98000 Blank Blank

After geocoding

Name Address Zip XCoord YCoord
Bill Smith 123 Orca St 98000 -122.345678 47.234567


Why geocoding precision important?

To see location patterns more clearly

You can map addresses by zip code, of course, without geocoding at the street level. This produces a very coarse understanding  compared to a address-level point map because you consider all those addresses to be in the same place: the zip code.

  After geocoding by zip code After geocoding by address

To summarize data by ring buffer or any custom shape

  • Which district office should handle the new client?  Geocode client addresses by street address and see which territory region they fall within.

  • How many customers fall with 5 minute drive of each proposed espresso outlet?  Geocode customers by street address, then overlay a 5-minute drivetime polygon.

  • Are capital improvement projects benefiting all legislative districts equally? Geocoding the street addresses of the capital projects then overlaying the legislative districts. 

  • Banks and insurance companies often report statistics by census tract. To determine the census tract for a loan or depositor, geocode the street addresses, overlay the tract map, then use Query > SQL Select to summarize by tract.

To target more precisely

  • We may make assumptions about households  based on the characteristics of the neighborhoods where they live.  If geocoded by street address, we can associate household records with smaller, more homogenous areas such as block groups.  This results in more accuracy. 

  • As shown below, the demographics of the block group areas (smaller) can be dramatically different than the demographics of zip codes (larger).

Higher income zip codes Higher income block groups

Geocoding: Part of modern corporate customer information systems

More and more Fortune 1000 corporations are geocoding all their customer addresses as a standard practice.  By making map position part of their overall corporate information system design, all areas of the organization take advantage of spatial analysis techniques.


Three Geocoding Software Alternatives:
MapInfo Pro, MapMarker, or MapInfo+MapMarker (hybrid)

MapInfo Pro:  The original street-level geocoder

The original way to geocode used MapInfo's built-in geocoding engine along with a street map.  MapInfo Corp pioneered this technique for PCs, releasing MapInfo (for DOS) in 1987.   MapInfo for Windows, released in 1992, also offered street level geocoding using displayable and user-editable street maps.

  • Geocoding is accessible via the MapInfo menu option   Table  > Geocode ...   Just add street map data.

  • Requires a street map with street names & address ranges: e.g., "StreetPro", "StreetInfo" or comparable.
    Note:  The most common version of StreetPro is "StreetPro Display", which does not have the address number ranges.

  • Uses an "abbreviation file" (e.g., to standardize some address components: e.g., "Street", "Str", and "St".

  • Can use a City or Zip code boundary map to distinguish addresses that occur in more than one place in a county.

Advantages of MapInfo Pro

  • Cheaper than MapMarker if & only if all addresses are in a few counties at most.

  • Street address information in street tables is completely editable.  Missing a street?  Just draw it and fill in the street name and address fields.  You can match against this new street immediately.

  • Can easily use new street map information generated by local governments.

  • Suitable for use in Mexico & other foreign countries for which MapMarker versions may not be available.

MapMarker:  Single-purpose stand-alone geocoder

  • A standalone geocoder software program, introduced by MapInfo Corp. in 1996 and now at Revision 12.1 (January 2007).   It can run without MapInfo Pro and is optimized to do one thing:  geocode large datasets quickly -- including data set covering many states. 

  • Primarily a regularly-updated data product, but includes a simple menu and dialog UI.

  • Available in multiple variants, each with different pricing and different levels of precision.  The most common version is MapMarker Plus.  Other versions include  MapMarker Zip4, MapMarker Std, MapMarker Plus.  There are also database specific extensions for SQL Server and Oracle.

Advantages of MapMarker

  • Cheaper, except for one-two-three county applications.

  • One-step geocoding, even if addresses are in many different counties across the US.

  • Cleans or standardizes addresses, zip codes, zip+4 codes on the fly.  Can produce USPS "CASS-certified" mailing lists.     [CASS-certified means lower postage rates for bulk mailers.]

  • Includes Zip+4 reference files and can automatically compute the Zip+4 code and geocode to the Zip+4 location as a fallback, if it cannot match to exact street address.

  • Very fast: SGSI has processed 1,000,000 records in under 1 hour in batch mode.

  • Adds census tract, block group, and block codes to the address record as part of its single-pass processing.  No separate SQL processing required.

  • Friendly, straightforward user-interface. Easy to use.

  • Is engineered as a true client-server application and can be used as the geocoding engine for a web server, for example.

  • More sophisticated "rule based" matching algorithms are better than those in MapInfo Pro.  Offers a better set of "close-match" candidates than MapInfo.

  • Can process sets of address files, running in "batch" mode.

  • While address and street data is not directly user-editable, power users can build & compile custom MapMarker-format databases and use them in concert with MapMarker's standard databases.

  • Server version is 100% Java, with Java and XML api's for integration with custom applications.

MapInfo Pro + MapMarker:  Best of both worlds

  • With MapInfo Pro 8.5 and MapMarker, users geocode MapInfo tables or selected records without leaving MapInfo Pro.

  • Table > Geocode Using Server ...









Improving Precision:
Enhanced address interpolation, Parcel-level, & Rooftop

Improved geocoding precision is possible with better underlying data and better software algorithms.

Since all geocoders rely on digital maps, geocoding becomes more precise as the underlying street maps, street names & street number content is improved.

There is a recent trend though, toward basing address geocoding improvements on entirely new digital map layers--not just street maps.

Address Interpolation

Most geocoding engines rely on house number interpolation to estimate the position of an exact street address.

This technique is excellent where the house number range reflects actual house numbers and where homes are evenly spaced along the block.

It can create a distorted picture, however, if the actual addresses along the block aren't evenly spaced or if the actual high-low house numbers are very different than the theoretical high-low house numbers.

This is the approach taken by most commercial geocoders.  E.g.,

Enhanced Address Interpolation

With enhanced interpolation, the geocoding system computes the *actual* high-low house numbers on the block, by reference to extra data beyond the street map.  Interpolation still occurs, but it is between more accurate high-low locations and the results are much better. 

This is the approach pioneered by MapInfo beginning with MapMarker Revision 12.0:

Parcel-level precision

Of course, enhanced interpolation solves only part of the problem.  In many cases, homes are *not* evenly spaced along the block. 

To resolve this problem, MapInfo has incorporated actual land parcel boundaries as an extra-cost option for MapMarker.  Users may specify that addresses be geocoded to either the centroid of the parcel polygon or to a point aligned with the parcel but offset a specific distance from the street center line.

Note:  This Parcel-level option does not include a visible parcel map layer.  Also, while millions of parcels are referenced, the coverage is not 100%.  Please contact SGSI at 206-224-0800 for details.

Software + Your data:  Custom dictionaries

The next step toward maximum geocoding precision is determining x,y coordinates based on the most important part of the property.  E.g., a delivery service may want to determine the lat-lon of the doorway.

To be continued ...


  Pricing (Ballpark examples)


MMkrP 12.x, 1 Yr Updates, Full US



MMkrP 12.x, 1 Yr Updates, 1 State



MMkrP 12.x, 1 Yr Updates, 1 State, Parcel P



StreetPro Streets with Addresses, 1 County



StreetPro Streets with Addresses, 1 State


The above prices are ballparks only and cover desktop use (not server) for 1 named user.  Substantial discounts apply for 3-Year Update Subscriptions.  Modest discounts apply for government users.  Please contact SGSI at 1-206-224-0800 or email us for more specific pricing. 

  Ready to order?

You can order MapMarker or StreetPro street data by simply calling SGSI at 1-206-224-0800 or via email

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