[postgis-users] Converting GMaps.getBounds to POLYGON ewkt format

[RAVI KUMAR]

Hi,
  nice to see some Indians on this wonderful list.
  I am a Geologist from Hyderabad. I use OpenJUMP, PostGIS (not very successful though) and GRASS GIS.
   
  Pl give your details.
  Namashkar
  Ravi Kumar

Babu Naidu <pbnaidu at gmail.com> wrote:
  Thanks Robert. That worked and I am going to use the concise format of MakeBox2D.
-Babu

  On 9/15/07, Robert Coup < robert.coup at onetrackmind.co.nz> wrote:  On 15/09/2007, Babu Naidu < pbnaidu at gmail.com> wrote:
> I am trying to convert Google Maps GMap.getBounds() (which returns LatLng
> for south west and LatLng for north east)
> to POLYGON( ) ewkt format. This is to query for points within that POLYGON. 
>
> I think I figured out the format and I would like to verify it with experts
> here. I have southwest Lat Lng and northeast LatLng
> considering Y=Lng and X=Lat
>
> POLYGON(maxY  maxX, 
> maxY  minX,
> minY  minX,
> minY  maxX,
> maxY  maxX)
>
> Is this the right way to create a POLYGON? could you please point me to docs
> if available that explain this format?

X should be Longitude, and Y Latitude. Always.

in WKT you need double-brackets for a polygon, and the common
convention is to do boxes in the following sequence:
POLYGON((minx miny, maxx miny, maxx maxy, minx maxy, minx miny)) 

If you don't need to make WKT you could do the following instead,
which creates a geometry you can use in queries, etc:
MakeBox2D(MakePoint(minx, miny), MakePoint(maxx, maxy))

hth,

Rob :)
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