[postgis-devel] Positional Operators

[David William Bitner]

In a normal Northern Hemisphere projection, above=north, below=south,
left=west, right=east.

On 7/6/06, Joel da Silva <js at cin.ufpe.br> wrote:
>
> Dear friends,
> I have a geographical database  in the PostreSQL 8.1
> I have realized some test with positional operators in the postgis
> e.g.:
>  for two geographical features (A and B), we have the following positional
> operators:
>
> completely at-left     A << B
> completely at-right   A >> B
>  at-left or overlaps at-left  A  &<  B
>  at-right or overlaps at-right  A  &>  B
>
> completely above A |>> B
> completely below A |<< B
> above or overlaps above A  |&> B
> below or overlaps below A  &<| B
>
>
> North-West       A |>> B AND A << B
> North-Est         A |>> B AND A >> B
> South-West        A <<| B AND A << B
> South-Est         A <<| B AND A >> B
>
>
> but, how I can to express the  North-of, South-of,  Est-of  and West-of
> positional   operators?
>
> somebody can  help me
> thanks for your attention
> best regards
> Joel
>
>
>
>
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>
>
>


-- 
************************************
David William Bitner
bitner at gyttja.org
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