Geocoding:

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Geocoding - Table to geocode may be an
ASCII, spreadsheet, dBase, or MapInfo
table - Referred to as the target table
- The target table is the attribute table that
we want to spatially locate on a map
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Geocoding - Table that will be used to
reference or match the attribute data
- Referred to as the Reference Database
or the Search Table - In this example, the
search table is the TIGER centerline file
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2 methods of Geocoding 1. Address
(Interpolation method)- places point along street
centerline
Target 1225 Main St.
2. Polygon- places point at centroid (weighted
center) of polygon
Target 44114
Reference
Zip code
1225 Main St
OR 1225 Main St
Parcels
Main St.
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Address (Interpolation) Method
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Steps to Geocode
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Classes of match results
Incorrect Match Data record matched to incorrect
segment. The house address value in the target
db is written wrong. ie. 1000 Main St. typed
wrong really should be 100 Main St. Nonmatch
that could be matched. A portion of the address
in the target db is written wrong. ie. Main
Ave. in target db but should be Main St. Correct
match Obviously, this is what we
want!!!! Correct Nonmatch (unmatchable record)
No match can occur ie. A new road is made, but
the information about the road has not been added
to the reference data
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The following slides step through
the geocoding process using the address method
(interpolation) in MapInfo
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1. Open the target db (table to geocode) 2.
Determine field to use to geocode 3. Run the
table of addresses through an address standarizer
(if available) 4. Determine if a field such as
such as zip code or city exists so that you use
the refine search option with a polygon file 5.
Create a new field to store the geocode result
code (code gives idea why matches did not occur)
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Reference db- Street Centerline
Determine the reference db to use. Determine the
key field that will be used as the match in the
reference table. Determine the field name of the
polygon file that contains the zip or city
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In MapInfo, Select Tablegt Geocode
1 the table used to find a x,y spatial
location 2 the field to use to locate
attempt to match to 4 3 the reference
data layer that already has a spatial
location 4 the field in the reference table
that is used to locate the value in field
2 of the table to geocode 5 a secondary
reference data layer (i.e. zip or city)
that allows for more accurate geocoding results-
(101 Main St in Berea or 101 Main St in
Parma)
6B
6A field value used to match to 6B of
the geocode table 6A MUST be filled in prior to
6B
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Geocoded points result using address matching to
street centerline Interpolation Method
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Result code values Any negative value means that
the record did not geocode The code may give
you an idea of the error.
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Geocoding using the polygon method
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Geocoding using both Interpolation and Polygon
Methods Comparison
Polygon Method
Interpolation Method
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