A little more about centroids...
While it may seem that MapInfo should correctly place the centroid of an
object at the geographic center of an object that isn't necessarily the
case. If you wanted to, you could export a mapinfo table (or
programmatically create one), and specify a "Center" X,Y for each region
object. By doing this you can override MapInfo's natural centroid creation
process while importing, and get a centroid anywhere you like. I naven't
actually tried putting the centroid outside of a region object, but I would
assume (...yah right!...) that would work.
Ian Erickson
AnalyGIS
http://www.analygis.com
----- Original Message -----
From: "C & K Townsend" <[EMAIL PROTECTED]>
To: "Steve Wallace" <[EMAIL PROTECTED]>
Cc: "Mike Hankins" <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>
Sent: Thursday, March 29, 2001 11:02 PM
Subject: Re: MI-L Centroids of objects
> Mike
> I'm a little inexperienced but I believe that Mapinfo creates a centroid
> by using something called a minimum bounding rectangle(MBR). In this
> scenario it is quite possible for Mapinfo to return a centroid position
> outside of the polygon in question. I know of no way around this.
> Regards
> Craig Townsend
> Guyra Shire Council
> NSW AUSTRALIA
>
> Steve Wallace wrote:
> >
> > Sounds like you have some spatial errors in this table. I've never seen
a
> > centroid outside an object. Even if you try and move a centroid outside
an
> > object by hand, MapInfo will give you an error.
> >
> > Use MapCheck (for older MapInfo versions), or Objects > Check Regions
(in
> > newer) to see if there are any problems with these regions.
> >
> > To re-cast all the centroids in a table, you can make the layer
editable,
> > select all regions, convert all to polylines, then convert all back to
> > regions.
> >
> > Steve Wallace
> >
> > ----- Original Message -----
> > From: "Mike Hankins" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Thursday, March 29, 2001 12:01 PM
> > Subject: MI-L Centroids of objects
> >
> > > Hello,
> > > I ran into a problem while updating a column. The wrong
territory
> > > value was being assigned to the object and I have figured it out that
the
> > > centroid is outside of the polygon. Is there a way to check a file to
see
> > > if the centroid of a object is outside of the polygon for that object?
I
> > > will have over 50 tables with as many as 3000 polygons in each table.
Is
> > > there a way to update the columns without using a centroid based
solution?
> > >
> > > Thanks to All,
> > >
> > > Mike Hankins
> > > COUNTRY Insurance and Finacial Services
> > >
> > >
> > >
> > >
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>
>
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