Outward buffering

Question

I get the ConvexHull of a set of polygons using ST_UNION and ST_CONVEXHULL functions using PostGIS. I want to know how to create an outward buffer of the created convexhull in PostGIS?

Answer 1

ST_ConvexHull() returns a Polygon. Using ST_Buffer() on the result will create an "outward" buffer.

SELECT ST_As_Text(ST_Buffer(ST_ConvexHull(ST_Union(the_geom)), 1)) FROM building_poly;