How to get a bounding polygon around points?

Question

I have a table with thousands of addresses in the form of dots.

Is there a function in postgis that will allow me to get a limited polygon around these points and return it as a polygon?

update I'm looking for a more complex polygon than just a bounding box

Answer 1

Your question may not be 100% clear what you mean as a more restrictive polygon. It can be understood as

• minimum bounding box (also known as MBR or envelope) for which you can use ST_Envelope , ST_Box2D or ST_Extent ,

• as a minimal geometry, covering all points in a given geometry, a convex envelope , in which case you can use ST_ConvexHull or even ST_ExteriorRing if your entrance will be a polygon,

• As Pimin noted in the comments below, ST_ConcaveHull is another option worth considering, available with PostGIS 2.0.0.

Answer 2

Of course ST_Extent: http://postgis.refractions.net/documentation/manual-1.4/ST_Extent.html