You could use a buffer procedure.  I would create a new table to hold the
buffer objects instead of ISSUE.TAB.  We could call it Issue_Buffers.TAB.
Give it the same structure by creating it from the Issue table.  Have this
new table editable, all 3 open.  Select all from the Issue table. Then
Objects>buffer objects, set it to buffer each object, set buffer distance to
only what is needed, 1 meter sounds like it would work.  The buffer regions
only will be created in the new table (Issues_Buffers), and it will have the
same data associated with the original points (be sure to check Value for
each field when the buffers are created).  Then query thusly: select * from
Issues_Buffers, Addresses where Issues_Buffers.obj contains Addresses.obj


I assume that Issue.ID <> Addr_ID, else you would select * from issue,
address where ISSUE_ID = ADDR_ID

William "Woody" Woodruff
Zoning Administrator
Charter Township of Union, Isabella County, Michigan
-84.80947000 43.61095100
2010 S Lincoln Rd, Mt. Pleasant, MI  48858
(989) 772 4600 EXT 41 - FAX (989) 773 1988
Visit our web site at http://www.geocities.com/ctuzoning/index.htm



-----Original Message-----
From: Munro, Alison [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 14, 2005 3:00 PM
To: [email protected]
Subject: MI-L Coordinate shift in Geocoding process


I have an address point table in coord system UTM-NAD83/Zone 17.

I am geocoding an issue table against it, using an address field in each
table for the matching.  About 25% of the issues geocode against the
addresses, which is acceptable for my purposes.  After geocoding I save
a copy of the issue table, also projected into UTM-NAD83/Zone 17. (I
have also tried NOT saving in UTM, with no difference in the result
below).

So far, so good.  Now for the problem.

I want to select the ADDR_ID and ISSUE_ID pairs from the two tables by
finding the coincident points.  Since the issues were geocoded against
the addresses, and about 1180 matched, this should not be a problem.
However when I perform an SQL-query with where clause "AddressPoints.obj
Intersects VXSISSUES_geo.obj", I only get 5 matches.  I have also tried
CONTAINS, CONTAINS ENTIRELY, WITHIN and ENTIRELY WITHIN with the same
result (either no matches, or at best 5).

When I zoom right in to an apparently coincident Address and Issue pair,
there is a slight shift of about 4cm between the two points - hence no
spatial coincidence.  Apparently, somewhere between the geocoding and/or
the projecting there has been a coordinate truncation or rounding.  (I
have also tried NOT projecting the issues into UTM, with no difference
in the result).

Any suggestions?  Workarounds?

Alison Munro
Information & Technology Mgmt Dept.
City of Vaughan
2141 Major Mackenzie Drive
Vaughan ON L6A 1T1


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