[postgis-devel] Re: Postgis Extension

strk at refractions.net strk at refractions.net
Mon Jul 4 12:10:13 PDT 2005


On Mon, Jul 04, 2005 at 03:55:59PM -0300, Joel da Silva wrote:
> strk,
> 
> I talk about  twelve possible positional relationships
> between two objects: (atNorth_of, atSouth_of, at_East_of,
> at_West_of, at_North-Est_of, at_North-West_of, at_South-
> East_of, at_South-West_of, Above, Below, at_Left_of and
> at_Right_of.
> For the first eight ones it is possible to specialize their
> meaning, that is, each of them can have the following prefix:
> Completely, Only, Partially, Also.
> 
> Seems to me that The postgis provides only above, below, Right and left
> operators.
> I am right?

Also Over{Right,Left,Above,Below}.
Combining them can give you the others.
For example, A North-West-of B could be expressed with:

	A |>> B AND A << B

Let's keep the discussion on postgis-devel so you to get other
opinions on this.

--strk;



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