This topic describes the ST_Scale function. This function scales a geometry object to a new size by multiplying its coordinate values with the corresponding factors.

Syntax

geometry  ST_Scale(geometry  geomA , float  xFactor , float  yFactor , float  zFactor);
geometry  ST_Scale(geometry  geomA , float  xFactor , float  yFactor);
geometry  ST_Scale(geometry  geom , geometry  factor);
geometry  ST_Scale(geometry  geom , geometry  factor , geometry  origin);

Parameters

Parameter Description
geomA/geom The geometry object that you want to specify.
xFactor The factor for the values of the x coordinate.
yFactor The factor for the values of the y coordinate.
zFactor The factor for the values of the y coordinate.
factor The scaling factor.
origin The origin of the scaling.

Description

  • You can specify the factor parameter to a 2D, 3DM, 3DZ, or 4D point object. This configuration ensures the scaling factor for all supported dimensions. If the xFactor, yFactor, or zFactor parameter is not specified, the scaling is not performed on the corresponding dimension of the geometry object.
  • This function supports circular strings, curves, polyhedral surfaces, triangles, triangulated irregular network (TIN) surfaces, and 3D objects.
  • This function supports geometry objects that contain m coordinates.
  • If you specify the origin parameter, the ST_Scale function immediately scales the geometry object in place. For example, you can specify the centroid of the geometry object as the scaling origin. If you do not specify the origin parameter, the ST_Scale function scales the geometry object relative to the actual origin of the geometry object. In this case, this function scales the geometry object by multiplying coordinate values by the values of the corresponding factor parameters.

Examples

  • Scales a geometry object by using the default parameter settings.
    SELECT ST_AsText(ST_Scale('LINESTRING(2 1,1 1)'::geometry,2,2));
      st_astext
---------------------
 LINESTRING(4 2,2 2)
(1 row)
  • Scales a geometry object by specifying the factor parameter.
    SELECT ST_AsText(ST_Scale('LINESTRING(2 1,1 1)'::geometry,'POINT(2 2)'::geometry));
      st_astext
---------------------
 LINESTRING(4 2,2 2)
(1 row)
  • Scales a geometry object by specifying the origin parameter.
    SELECT
    ST_Scale(g,factor),
  ST_Scale(g,factor,'POINT(2 1)'::geometry),g
  from (select 'LINESTRING(2 1,1 1,1 2)'::geometry as g,'POINT(3 3)'::geometry as factor) as t;
1