ST_Affine method for type ST

ST_Affine method for type ST_Geometry

Returns a new geometry that is the result of applying the specified 3-D affine transformation.

Syntax

geometry-expression.ST_Affine(a00,a01,a02,a10,a11,a12,a20,a21,a22,xoff,yoff,zoff)

Parameters

Name	Type	Description
a00	DOUBLE	The affine matrix element in row 0, column 0
a01	DOUBLE	The affine matrix element in row 0, column 1
a02	DOUBLE	The affine matrix element in row 0, column 2
a10	DOUBLE	The affine matrix element in row 1, column 0
a11	DOUBLE	The affine matrix element in row 1, column 1
a12	DOUBLE	The affine matrix element in row 1, column 2
a20	DOUBLE	The affine matrix element in row 2, column 0
a21	DOUBLE	The affine matrix element in row 2, column 1
a22	DOUBLE	The affine matrix element in row 2, column 2
xoff	DOUBLE	The x offset for translation
yoff	DOUBLE	The y offset for translation
zoff	DOUBLE	The z offset for translation

Returns

ST_Geometry Returns a new geometry that is the result of the specified transformation.
The spatial reference system identifier of the result is the same as the spatial reference system of the geometry-expression.

Remarks

An affine transformation combines rotation, translation and scaling into a single method call. The affine transform is defined using matrix multiplication.

For a point (x,y,z), the result (x',y',z') is computed as follows:

/ x' \   / a00 a01 a02 xoff \   / x \
| y' | = | a10 a11 a12 yoff | * | y |
| z' |   | a20 a21 a22 yoff |   | z |
\ w' /   \ 0   0   0   1    /   \ 1 /

Note

This method can not be used with geometries in round-Earth spatial reference system.

Standards and compatibility

Example

The following returns the result LineString (5 6, 5 3, 9 3). The X values are translated by 5 and the Y values are translated by -1.

SELECT Shape.ST_Affine( 1,0,0, 0,1,0, 0,0,1, 5,-1,0 )
FROM SpatialShapes WHERE ShapeID = 5

The following returns the result LineString (.698833 6.965029, .399334 3.980017, 4.379351 3.580683). The Shape is rotated around the Z axis by 0.1 radians (about 5.7 degrees).

SELECT Shape.ST_Affine( cos(0.1),sin(0.1),0, -sin(0.1),cos(0.1),0, 0,0,1, 0,0,0 )
FROM SpatialShapes WHERE ShapeID = 5

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