> -----Oorspronkelijk bericht-----
> Van: Ronald Louer
> Verzonden: donderdag 25 januari 2001 10:04
> Aan: 'Erin Rubio'
> Onderwerp: RE: MI-L overlap of 3 or more polygons
>
> Hello Erin,
>
> If you have two tables this query will show the proportion overlap of
> objects which overlap:
>
> Select NL_prov.Province, NL_Urban.CITY,
> proportionoverlap(NL_Urban.obj, NL_prov.obj)
> From NL_Urban, NL_prov
> where NL_Urban.obj partly within NL_prov.obj
>
> The result is a list of provinces and all urban regions within these
> provinces. Also the overlap of
> the urban region with the province will be indicated. An urban region
> will have 1 (= 100%) as it is completely within
> a province, and otherwise will indicate the proportion of overlap (for
> example 0.5 for 50%).
>
> Using INTERSECT instead of PARTLY WITHIN will select adjacent regions!
> Partly within will select regions which are at least for a part within
> another region,
> so adjacent regions will not be selected (unless overlapping).
>
> If you have one table then just make a copy of it and remember that 1
> will probably be the object itself.
>
> Spatial operators are poorly documented in MapInfo Professional.
> It's better to use the MapBasic help and MapBasic manuals.
>
> Hope this helps,
>
>
> Ronald Louer
> Consultant GIS
> InterStation Benelux BV
>
>
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