This topic describes the ST_ConvexHull function, which obtains the minimum convex geometry that encloses all geometries within a raster.
Syntax
geometry ST_ConvexHull(raster source);
geometry ST_ConvexHull(raster source,
integer pyramid);Parameters
| Parameter | Description |
|---|
| Parameter | Description |
|---|---|
| source | The raster whose minimum convex geometry you want to obtain. |
| pyramid | The pyramid level at which the raster resides. Valid values start from 0. Default value: 0. |
Description
This function obtains the minimum convex geometry that encloses all geometries within a raster.
Example
SELECT st_astext(st_convexhull(rast_object))
FROM raster_table;
----------------------------------------------------
POLYGON((-180 90,180 90,180 -90,-180 -90,-180 90))
--Specify the pyramid level at which the raster resides.
SELECT st_astext(st_convexhull(rast_object, 1))
FROM raster_table;
----------------------------------------------------
POLYGON((-180 90,180 90,180 -90,-180 -90,-180 90)) 
