[postgis-users] getting a square/rectangle arround a point

[Kevin Neufeld]

Unless I misunderstand what you are after, why don't you simply expand the bounding box of the point by your required 
amount?

ie.
SELECT
   ST_AsText(geom),
   ST_AsText(ST_Expand(geom, 2))
FROM (SELECT 'POINT(5 5)'::geometry AS geom) AS a;

  st_astext  |           st_astext
------------+--------------------------------
  POINT(5 5) | POLYGON((3 3,3 7,7 7,7 3,3 3))
(1 row)


-- Or create a rectangle from a point
SELECT
   ST_AsText(geom),
   ST_AsText(
     ST_Envelope(ST_MakeLine(
       ST_MakePoint(ST_X(geom) - 3, ST_Y(geom) - 2),
       ST_MakePoint(ST_X(geom) + 3, ST_Y(geom) + 2)
     ))
   )
FROM (SELECT 'POINT(5 5)'::geometry AS geom) AS a;

  st_astext  |           st_astext
------------+--------------------------------
  POINT(5 5) | POLYGON((2 3,2 7,8 7,8 3,2 3))
(1 row)


-- Kevin

Daniel Grum wrote:
> Dear Mailing-List,
> 
> I want to create a square/rectangle around a point-->via box2d(geometry) 
> or buffer(geometry, double precision) for example.
> 
> If I have this rectangle I want to intersect this with another 
> polygon--> saved in the (geodata) table: wald_by column: the_geom, to 
> get information about the area the the "lumberjack" can dig.
> The point in the middle of the rectangle = the point that is saved in a 
> table in my database in the table: holzfaeller in the column the_geom!
> 
> Is this possible to solve?
> Do I have to save this calculated square/rectangle in an extra/own table?
> 
> Thanks for every help.
> 
> Daniel
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