DuckDB function ST_Affine — ST

Applies an affine transformation to a geometry.

For the 2D variant, the transformation matrix is defined as follows:

| a b xoff |
| d e yoff |
| 0 0 1    |

For the 3D variant, the transformation matrix is defined as follows:

| a b c xoff |
| d e f yoff |
| g h i zoff |
| 0 0 0 1    |

The transformation is applied to all vertices of the geometry.

Usage

ST_Affine(geom, a, b, c, d, e, f, g, h, i, xoff, yoff, zoff)

Arguments

geom: GEOMETRY
a: DOUBLE
b: DOUBLE
c: DOUBLE
d: DOUBLE
e: DOUBLE
f: DOUBLE
g: DOUBLE
h: DOUBLE
i: DOUBLE
xoff: DOUBLE
yoff: DOUBLE
zoff: DOUBLE

Value

GEOMETRY

Overloads

ST_Affine(geom = GEOMETRY, a = DOUBLE, b = DOUBLE, c = DOUBLE, d = DOUBLE, e = DOUBLE, f = DOUBLE, g = DOUBLE, h = DOUBLE, i = DOUBLE, xoff = DOUBLE, yoff = DOUBLE, zoff = DOUBLE)
ST_Affine(geom = GEOMETRY, a = DOUBLE, b = DOUBLE, d = DOUBLE, e = DOUBLE, xoff = DOUBLE, yoff = DOUBLE)

Provided by

The spatial extension (LOAD spatial;).

SQL examples

-- Translate a point by (2, 3)
SELECT ST_Affine(ST_Point(1, 1),
                 1, 0,   -- a, b
                 0, 1,   -- d, e
                 2, 3);  -- xoff, yoff
-- POINT (3 4)
--
-- -- Scale a geometry by factor 2 in X and Y
-- SELECT ST_Affine(ST_Point(1, 1),
--                  2, 0, 0,   -- a, b, c
--                  0, 2, 0,   -- d, e, f
--                  0, 0, 1,   -- g, h, i
--                  0, 0, 0);  -- xoff, yoff, zoff
-- POINT (2 2)