# Geometry Editors

ST_AddPoint Adds a point to a LineString before point <position> (0-based index).
geometry `ST_AddPoint` geometry linestring geometry point geometry `ST_AddPoint` geometry linestring geometry point integer position

### Description

Adds a point to a LineString before point <position> (0-based index). Third parameter can be omitted or set to -1 for appending.

Availability: 1.1.0

&Z_support;

### Examples

    		--guarantee all linestrings in a table are closed
    		--by adding the start point of each linestring to the end of the line string
    		--only for those that are not closed
    		UPDATE sometable
    		SET the_geom = ST_AddPoint(the_geom, ST_StartPoint(the_geom))
    		FROM sometable
    		WHERE ST_IsClosed(the_geom) = false;

    		--Adding point to a 3-d line
    		SELECT ST_AsEWKT(ST_AddPoint(ST_GeomFromEWKT('LINESTRING(0 0 1, 1 1 1)'), ST_MakePoint(1, 2, 3)));

    		--result
    		st_asewkt
    		----------
    		LINESTRING(0 0 1,1 1 1,1 2 3)

### See Also

,

ST_Affine Applies a 3d affine transformation to the geometry to do things like translate, rotate, scale in one step.
geometry `ST_Affine` geometry geomA float a float b float c float d float e float f float g float h float i float xoff float yoff float zoff geometry `ST_Affine` geometry geomA float a float b float d float e> float xoff float yoff

### Description

Applies a 3d affine transformation to the geometry to do things like translate, rotate, scale in one step.

Version 1: The call

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

represents the transformation matrix

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

and the vertices are transformed as follows:

    x' = a*x + b*y + c*z + xoff
    y' = d*x + e*y + f*z + yoff
    z' = g*x + h*y + i*z + zoff

All of the translate / scale functions below are expressed via such an affine transformation.

Version 2: Applies a 2d affine transformation to the geometry. The call

    ST_Affine(geom, a, b, d, e, xoff, yoff)

represents the transformation matrix

    /  a  b  0  xoff  \       /  a  b  xoff  \
    |  d  e  0  yoff  | rsp.  |  d  e  yoff  |
    |  0  0  1     0  |       \  0  0     1  /
    \  0  0  0     1  /

and the vertices are transformed as follows:

    x' = a*x + b*y + xoff
    y' = d*x + e*y + yoff
    z' = z

This method is a subcase of the 3D method above.

Availability: 1.1.2. Name changed from Affine to ST_Affine in 1.2.2

Prior to 1.3.4, this function crashes if used with geometries that contain CURVES. This is fixed in 1.3.4+

&Z_support;

&curve_support;

### Examples

    --Rotate a 3d line 180 degrees about the z axis.  Note this is long-hand for doing ST_RotateZ();
     SELECT ST_AsEWKT(ST_Affine(the_geom,  cos(pi()), -sin(pi()), 0,  sin(pi()), cos(pi()), 0,  0, 0, 1,  0, 0, 0)) As using_affine,
    	 ST_AsEWKT(ST_RotateZ(the_geom, pi())) As using_rotatez
    	FROM (SELECT ST_GeomFromEWKT('LINESTRING(1 2 3, 1 4 3)') As the_geom) As foo;
    		using_affine         |        using_rotatez
    -----------------------------+-----------------------------
     LINESTRING(-1 -2 3,-1 -4 3) | LINESTRING(-1 -2 3,-1 -4 3)
    (1 row)

    --Rotate a 3d line 180 degrees in both the x and z axis
    SELECT ST_AsEWKT(ST_Affine(the_geom, cos(pi()), -sin(pi()), 0, sin(pi()), cos(pi()), -sin(pi()), 0, sin(pi()), cos(pi()), 0, 0, 0))
    	FROM (SELECT ST_GeomFromEWKT('LINESTRING(1 2 3, 1 4 3)') As the_geom) As foo;
    		   st_asewkt
    -------------------------------
     LINESTRING(-1 -2 -3,-1 -4 -3)
    (1 row)

### See Also

, , ,

ST_Force_2D Forces the geometries into a "2-dimensional mode" so that all output representations will only have the X and Y coordinates.
geometry `ST_Force_2D` geometry geomA

### Description

Forces the geometries into a "2-dimensional mode" so that all output representations will only have the X and Y coordinates. This is useful for force OGC-compliant output (since OGC only specifies 2-D geometries).

&curve_support;

### Examples

    SELECT ST_AsEWKT(ST_Force_2D(ST_GeomFromEWKT('CIRCULARSTRING(1 1 2, 2 3 2, 4 5 2, 6 7 2, 5 6 2)')));
    		st_asewkt
    -------------------------------------
    CIRCULARSTRING(1 1,2 3,4 5,6 7,5 6)

    SELECT  ST_AsEWKT(ST_Force_2D('POLYGON((0 0 2,0 5 2,5 0 2,0 0 2),(1 1 2,3 1 2,1 3 2,1 1 2))'));

    				  st_asewkt
    ----------------------------------------------
     POLYGON((0 0,0 5,5 0,0 0),(1 1,3 1,1 3,1 1))

### See Also

ST_Force_3D Forces the geometries into XYZ mode. This is an alias for ST_Force_3DZ.
geometry `ST_Force_3D` geometry geomA

### Description

Forces the geometries into XYZ mode. This is an alias for ST_Force_3DZ. If a geometry has no Z component, then a 0 Z coordinate is tacked on.

&Z_support;

&curve_support;

### Examples

    		--Nothing happens to an already 3D geometry
    		SELECT ST_AsEWKT(ST_Force_3D(ST_GeomFromEWKT('CIRCULARSTRING(1 1 2, 2 3 2, 4 5 2, 6 7 2, 5 6 2)')));
    				   st_asewkt
    -----------------------------------------------
     CIRCULARSTRING(1 1 2,2 3 2,4 5 2,6 7 2,5 6 2)

    SELECT  ST_AsEWKT(ST_Force_3D('POLYGON((0 0,0 5,5 0,0 0),(1 1,3 1,1 3,1 1))'));

    						 st_asewkt
    --------------------------------------------------------------
     POLYGON((0 0 0,0 5 0,5 0 0,0 0 0),(1 1 0,3 1 0,1 3 0,1 1 0))

### See Also

, , ,

ST_Force_3DZ Forces the geometries into XYZ mode. This is a synonym for ST_Force_3D.
geometry `ST_Force_3DZ` geometry geomA

### Description

Forces the geometries into XYZ mode. This is a synonym for ST_Force_3DZ. If a geometry has no Z component, then a 0 Z coordinate is tacked on.

&Z_support;

&curve_support;

### Examples

    --Nothing happens to an already 3D geometry
    SELECT ST_AsEWKT(ST_Force_3DZ(ST_GeomFromEWKT('CIRCULARSTRING(1 1 2, 2 3 2, 4 5 2, 6 7 2, 5 6 2)')));
    				   st_asewkt
    -----------------------------------------------
     CIRCULARSTRING(1 1 2,2 3 2,4 5 2,6 7 2,5 6 2)

    SELECT  ST_AsEWKT(ST_Force_3DZ('POLYGON((0 0,0 5,5 0,0 0),(1 1,3 1,1 3,1 1))'));

    						 st_asewkt
    --------------------------------------------------------------
     POLYGON((0 0 0,0 5 0,5 0 0,0 0 0),(1 1 0,3 1 0,1 3 0,1 1 0))

### See Also

, , ,

ST_Force_3DM Forces the geometries into XYM mode.
geometry `ST_Force_3DM` geometry geomA

### Description

Forces the geometries into XYM mode. If a geometry has no M component, then a 0 M coordinate is tacked on. If it has a Z component, then Z is removed

&curve_support;

### Examples

    --Nothing happens to an already 3D geometry
    SELECT ST_AsEWKT(ST_Force_3DM(ST_GeomFromEWKT('CIRCULARSTRING(1 1 2, 2 3 2, 4 5 2, 6 7 2, 5 6 2)')));
    				   st_asewkt
    ------------------------------------------------
     CIRCULARSTRINGM(1 1 0,2 3 0,4 5 0,6 7 0,5 6 0)

    SELECT  ST_AsEWKT(ST_Force_3DM('POLYGON((0 0 1,0 5 1,5 0 1,0 0 1),(1 1 1,3 1 1,1 3 1,1 1 1))'));

    						  st_asewkt
    ---------------------------------------------------------------
     POLYGONM((0 0 0,0 5 0,5 0 0,0 0 0),(1 1 0,3 1 0,1 3 0,1 1 0))

### See Also

, , , ,

ST_Force_4D Forces the geometries into XYZM mode.
geometry `ST_Force_4D` geometry geomA

### Description

Forces the geometries into XYZM mode. 0 is tacked on for missing Z and M dimensions.

&Z_support;

&curve_support;

### Examples

    --Nothing happens to an already 3D geometry
    SELECT ST_AsEWKT(ST_Force_4D(ST_GeomFromEWKT('CIRCULARSTRING(1 1 2, 2 3 2, 4 5 2, 6 7 2, 5 6 2)')));
    						st_asewkt
    ---------------------------------------------------------
     CIRCULARSTRING(1 1 2 0,2 3 2 0,4 5 2 0,6 7 2 0,5 6 2 0)

    SELECT  ST_AsEWKT(ST_Force_4D('MULTILINESTRINGM((0 0 1,0 5 2,5 0 3,0 0 4),(1 1 1,3 1 1,1 3 1,1 1 1))'));

    									  st_asewkt
    --------------------------------------------------------------------------------------
     MULTILINESTRING((0 0 0 1,0 5 0 2,5 0 0 3,0 0 0 4),(1 1 0 1,3 1 0 1,1 3 0 1,1 1 0 1))

### See Also

, , ,

ST_Force_Collection Converts the geometry into a GEOMETRYCOLLECTION.
geometry `ST_Force_Collection` geometry geomA

### Description

Converts the geometry into a GEOMETRYCOLLECTION. This is useful for simplifying the WKB representation.

Availability: 1.2.2, prior to 1.3.4 this function will crash with Curves. This is fixed in 1.3.4+

&Z_support;

&curve_support;

### Examples

    SELECT  ST_AsEWKT(ST_Force_Collection('POLYGON((0 0 1,0 5 1,5 0 1,0 0 1),(1 1 1,3 1 1,1 3 1,1 1 1))'));

    								   st_asewkt
    ----------------------------------------------------------------------------------
     GEOMETRYCOLLECTION(POLYGON((0 0 1,0 5 1,5 0 1,0 0 1),(1 1 1,3 1 1,1 3 1,1 1 1)))

      SELECT ST_AsText(ST_Force_Collection('CIRCULARSTRING(220227 150406,2220227 150407,220227 150406)'));
    								   st_astext
    --------------------------------------------------------------------------------
     GEOMETRYCOLLECTION(CIRCULARSTRING(220227 150406,2220227 150407,220227 150406))
    (1 row)

### See Also

, , , ,

ST_ForceRHR Forces the orientation of the vertices in a polygon to follow the Right-Hand-Rule.
boolean `ST_ForceRHR` geometry g

### Description

Forces the orientation of the vertices in a polygon to follow the Right-Hand-Rule. In GIS terminology, this means that the area that is bounded by the polygon is to the right of the boundary. In particular, the exterior ring is orientated in a clockwise direction and the interior rings in a counter-clockwise direction.

&Z_support;

### Examples

    SELECT ST_AsEWKT(
      ST_ForceRHR(
    	'POLYGON((0 0 2, 5 0 2, 0 5 2, 0 0 2),(1 1 2, 1 3 2, 3 1 2, 1 1 2))'
      )
    );
    						  st_asewkt
    --------------------------------------------------------------
     POLYGON((0 0 2,0 5 2,5 0 2,0 0 2),(1 1 2,3 1 2,1 3 2,1 1 2))
    (1 row)

### See Also

, ,

ST_LineMerge Returns a (set of) LineString(s) formed by sewing together a MULTILINESTRING.
geometry `ST_LineMerge` geometry amultilinestring

### Description

Returns a (set of) LineString(s) formed by sewing together the constituent line work of a MULTILINESTRING.

Only use with MULTILINESTRING/LINESTRINGs. If you feed a polygon or geometry collection into this function, it will return an empty GEOMETRYCOLLECTION

Availability: 1.1.0

requires GEOS >= 2.1.0

### Examples

    SELECT ST_AsText(ST_LineMerge(
    ST_GeomFromText('MULTILINESTRING((-29 -27,-30 -29.7,-36 -31,-45 -33),(-45 -33,-46 -32))')
    		)
    );
    st_astext
    --------------------------------------------------------------------------------------------------
    LINESTRING(-29 -27,-30 -29.7,-36 -31,-45 -33,-46 -32)
    (1 row)

    --If can't be merged - original MULTILINESTRING is returned
    SELECT ST_AsText(ST_LineMerge(
    ST_GeomFromText('MULTILINESTRING((-29 -27,-30 -29.7,-36 -31,-45 -33),(-45.2 -33.2,-46 -32))')
    )
    );
    st_astext
    ----------------
    MULTILINESTRING((-45.2 -33.2,-46 -32),(-29 -27,-30 -29.7,-36 -31,-45 -33))

### See Also

,

ST_CollectionExtract Given a GEOMETRYCOLLECTION, returns a MULTI* geometry consisting only of the specified type. Sub-geometries that are not the specified type are ignored. If there are no sub-geometries of the right type, an EMPTY collection will be returned. Only points, lines and polygons are supported. Type numbers are 1 == POINT, 2 == LINESTRING, 3 == POLYGON.
geometry `ST_CollectionExtract` geometry collection integer type

### Description

Given a GEOMETRYCOLLECTION, returns a MULTI* geometry consisting only of the specified type. Sub-geometries that are not the specified type are ignored. If there are no sub-geometries of the right type, an EMPTY collection will be returned. Only points, lines and polygons are supported. Type numbers are 1 == POINT, 2 == LINESTRING, 3 == POLYGON.

Availability: 1.5.0

### Examples

    -- Constants: 1 == POINT, 2 == LINESTRING, 3 == POLYGON
    SELECT ST_AsText(ST_CollectionExtract(ST_GeomFromText('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(POINT(0 0)))'),1));
    st_astext
    ---------------
    MULTIPOINT(0 0)
    (1 row)

    SELECT ST_AsText(ST_CollectionExtract(ST_GeomFromText('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1)),LINESTRING(2 2, 3 3))'),2));
    st_astext
    ---------------
    MULTILINESTRING((0 0, 1 1), (2 2, 3 3))
    (1 row)

### See Also

ST_Multi Returns the geometry as a MULTI* geometry. If the geometry is already a MULTI*, it is returned unchanged.
geometry `ST_Multi` geometry g1

### Description

Returns the geometry as a MULTI* geometry. If the geometry is already a MULTI*, it is returned unchanged.

### Examples

    SELECT ST_AsText(ST_Multi(ST_GeomFromText('POLYGON((743238 2967416,743238 2967450,
    			743265 2967450,743265.625 2967416,743238 2967416))')));
    			st_astext
    			--------------------------------------------------------------------------------------------------
    			MULTIPOLYGON(((743238 2967416,743238 2967450,743265 2967450,743265.625 2967416,
    			743238 2967416)))
    			(1 row)

### See Also

ST_RemovePoint Removes point from a linestring. Offset is 0-based.
geometry `ST_RemovePoint` geometry linestring integer offset

### Description

Removes point from a linestring. Useful for turning a closed ring into an open line string

Availability: 1.1.0

&Z_support;

### Examples

    --guarantee no LINESTRINGS are closed
    --by removing the end point.  The below assumes the_geom is of type LINESTRING
    UPDATE sometable
    	SET the_geom = ST_RemovePoint(the_geom, ST_NPoints(the_geom) - 1)
    	FROM sometable
    	WHERE ST_IsClosed(the_geom) = true;

### See Also

, ,

ST_Reverse Returns the geometry with vertex order reversed.
geometry `ST_Reverse` geometry g1

### Description

Can be used on any geometry and reverses the order of the vertexes.

### Examples

    SELECT ST_AsText(the_geom) as line, ST_AsText(ST_Reverse(the_geom)) As reverseline
    FROM
    (SELECT ST_MakeLine(ST_MakePoint(1,2),
    		ST_MakePoint(1,10)) As the_geom) as foo;
    --result
    		line         |     reverseline
    ---------------------+----------------------
    LINESTRING(1 2,1 10) | LINESTRING(1 10,1 2)

ST_Rotate This is a synonym for ST_RotateZ
geometry `ST_Rotate` geometry geomA float rotZRadians

### Description

This is a synonym for ST_RotateZ.. Rotates geometry rotZRadians about the Z-axis.

Availability: 1.1.2. Name changed from Rotate to ST_Rotate in 1.2.2

&Z_support;

&curve_support;

### Examples

### See Also

, , ,

ST_RotateX Rotate a geometry rotRadians about the X axis.
geometry `ST_RotateX` geometry geomA float rotRadians

### Description

Rotate a geometry geomA - rotRadians about the X axis.

`ST_RotateX(geomA, rotRadians)` is short-hand for `ST_Affine(geomA, 1, 0, 0, 0, cos(rotRadians), -sin(rotRadians), 0, sin(rotRadians), cos(rotRadians), 0, 0, 0)`.

Availability: 1.1.2. Name changed from RotateX to ST_RotateX in 1.2.2

&Z_support;

### Examples

    --Rotate a line 90 degrees along x-axis
    SELECT ST_AsEWKT(ST_RotateX(ST_GeomFromEWKT('LINESTRING(1 2 3, 1 1 1)'), pi()/2));
    		 st_asewkt
    ---------------------------
     LINESTRING(1 -3 2,1 -1 1)

### See Also

, ,

ST_RotateY Rotate a geometry rotRadians about the Y axis.
geometry `ST_RotateY` geometry geomA float rotRadians

### Description

Rotate a geometry geomA - rotRadians about the y axis.

`ST_RotateY(geomA, rotRadians)` is short-hand for `ST_Affine(geomA, cos(rotRadians), 0, sin(rotRadians), 0, 1, 0, -sin(rotRadians), 0, cos(rotRadians), 0, 0, 0)`.

Availability: 1.1.2. Name changed from RotateY to ST_RotateY in 1.2.2

&Z_support;

### Examples

    --Rotate a line 90 degrees along y-axis
     SELECT ST_AsEWKT(ST_RotateY(ST_GeomFromEWKT('LINESTRING(1 2 3, 1 1 1)'), pi()/2));
    		 st_asewkt
    ---------------------------
     LINESTRING(3 2 -1,1 1 -1)

### See Also

, , , Rotate around Point, Create Ellipse functions

ST_RotateZ Rotate a geometry rotRadians about the Z axis.
geometry `ST_RotateZ` geometry geomA float rotRadians

### Description

Rotate a geometry geomA - rotRadians about the Z axis.

`ST_RotateZ(geomA, rotRadians)` is short-hand for `SELECT ST_Affine(geomA, cos(rotRadians), -sin(rotRadians), 0, sin(rotRadians), cos(rotRadians), 0, 0, 0, 1, 0, 0, 0)`.

Availability: 1.1.2. Name changed from RotateZ to ST_RotateZ in 1.2.2

Prior to 1.3.4, this function crashes if used with geometries that contain CURVES. This is fixed in 1.3.4+

&Z_support;

&curve_support;

### Examples

    --Rotate a line 90 degrees along z-axis
    SELECT ST_AsEWKT(ST_RotateZ(ST_GeomFromEWKT('LINESTRING(1 2 3, 1 1 1)'), pi()/2));
    		 st_asewkt
    ---------------------------
     LINESTRING(-2 1 3,-1 1 1)

     --Rotate a curved circle around z-axis
    SELECT ST_AsEWKT(ST_RotateZ(the_geom, pi()/2))
    FROM (SELECT ST_LineToCurve(ST_Buffer(ST_GeomFromText('POINT(234 567)'), 3)) As the_geom) As foo;

    													   st_asewkt
    ----------------------------------------------------------------------------------------------------------------------------
     CURVEPOLYGON(CIRCULARSTRING(-567 237,-564.87867965644 236.12132034356,-564 234,-569.12132034356 231.87867965644,-567 237))

### See Also

, , , Rotate around Point, Create Ellipse functions

ST_Scale Scales the geometry to a new size by multiplying the ordinates with the parameters. Ie: ST_Scale(geom, Xfactor, Yfactor, Zfactor).
geometry `ST_Scale` geometry geomA float XFactor float YFactor float ZFactor geometry `ST_Scale` geometry geomA float XFactor float YFactor

### Description

Scales the geometry to a new size by multiplying the ordinates with the parameters. Ie: ST_Scale(geom, Xfactor, Yfactor, Zfactor).

`ST_Scale(geomA, XFactor, YFactor, ZFactor)` is short-hand for `ST_Affine(geomA, XFactor, 0, 0, 0, YFactor, 0, 0, 0, ZFactor, 0, 0, 0)`.

Prior to 1.3.4, this function crashes if used with geometries that contain CURVES. This is fixed in 1.3.4+

Availability: 1.1.0.

&Z_support;

&curve_support;

### Examples

    --Version 1: scale X, Y, Z
    SELECT ST_AsEWKT(ST_Scale(ST_GeomFromEWKT('LINESTRING(1 2 3, 1 1 1)'), 0.5, 0.75, 0.8));
    			  st_asewkt
    --------------------------------------
     LINESTRING(0.5 1.5 2.4,0.5 0.75 0.8)

    --Version 2: Scale X Y
     SELECT ST_AsEWKT(ST_Scale(ST_GeomFromEWKT('LINESTRING(1 2 3, 1 1 1)'), 0.5, 0.75));
    			st_asewkt
    ----------------------------------
     LINESTRING(0.5 1.5 3,0.5 0.75 1)

### See Also

,

ST_Segmentize Return a modified geometry having no segment longer than the given distance. Distance computation is performed in 2d only.
geometry `ST_Segmentize` geometry geomA float max_length

### Description

Returns a modified geometry having no segment longer than the given distance. Distance computation is performed in 2d only.

Availability: 1.2.2

This will only increase segments. It will not lengthen segments shorter than max length

### Examples

    SELECT ST_AsText(ST_Segmentize(
    ST_GeomFromText('MULTILINESTRING((-29 -27,-30 -29.7,-36 -31,-45 -33),(-45 -33,-46 -32))')
    		,5)
    );
    st_astext
    --------------------------------------------------------------------------------------------------
    MULTILINESTRING((-29 -27,-30 -29.7,-34.886615700134 -30.758766735029,-36 -31,
    -40.8809353009198 -32.0846522890933,-45 -33),
    (-45 -33,-46 -32))
    (1 row)

    SELECT ST_AsText(ST_Segmentize(ST_GeomFromText('POLYGON((-29 28, -30 40, -29 28))'),10));
    st_astext
    -----------------------
    POLYGON((-29 28,-29.8304547985374 37.9654575824488,-30 40,-29.1695452014626 30.0345424175512,-29 28))
    (1 row)

### See Also

ST_SetPoint Replace point N of linestring with given point. Index is 0-based.
geometry `ST_SetPoint` geometry linestring integer zerobasedposition geometry point

### Description

Replace point N of linestring with given point. Index is 0-based. This is especially useful in triggers when trying to maintain relationship of joints when one vertex moves.

Availability: 1.1.0

&Z_support;

### Examples

    --Change first point in line string from -1 3 to -1 1
    SELECT ST_AsText(ST_SetPoint('LINESTRING(-1 2,-1 3)', 0, 'POINT(-1 1)'));
    	   st_astext
    -----------------------
     LINESTRING(-1 1,-1 3)

    ---Change last point in a line string (lets play with 3d linestring this time)
    SELECT ST_AsEWKT(ST_SetPoint(foo.the_geom, ST_NumPoints(foo.the_geom) - 1, ST_GeomFromEWKT('POINT(-1 1 3)')))
    FROM (SELECT ST_GeomFromEWKT('LINESTRING(-1 2 3,-1 3 4, 5 6 7)') As the_geom) As foo;
    	   st_asewkt
    -----------------------
    LINESTRING(-1 2 3,-1 3 4,-1 1 3)

### See Also

,, , ,

ST_SetSRID Sets the SRID on a geometry to a particular integer value.
geometry `ST_SetSRID` geometry geom integer srid

### Description

Sets the SRID on a geometry to a particular integer value. Useful in constructing bounding boxes for queries.

This function does not transform the geometry coordinates in any way - it simply sets the meta data defining the spatial reference system the geometry is assumed to be in. Use if you want to transform the geometry into a new projection.

&sfs_compliant;

&curve_support;

### Examples

-- Mark a point as WGS 84 long lat --

    SELECT ST_SetSRID(ST_Point(-123.365556, 48.428611),4326) As wgs84long_lat;
    -- the ewkt representation (wrap with ST_AsEWKT) -
    SRID=4326;POINT(-123.365556 48.428611)

-- Mark a point as WGS 84 long lat and then transform to web mercator (Spherical Mercator) --

    SELECT ST_Transform(ST_SetSRID(ST_Point(-123.365556, 48.428611),4326),3785) As spere_merc;
    -- the ewkt representation (wrap with ST_AsEWKT) -
    SRID=3785;POINT(-13732990.8753491 6178458.96425423)

### See Also

, , , ,,

ST_SnapToGrid Snap all points of the input geometry to the grid defined by its origin and cell size. Remove consecutive points falling on the same cell, eventually returning NULL if output points are not enough to define a geometry of the given type. Collapsed geometries in a collection are stripped from it. Useful for reducing precision.
geometry `ST_SnapToGrid` geometry geomA float originX float originY float sizeX float sizeY geometry `ST_SnapToGrid` geometry geomA float sizeX float sizeY geometry `ST_SnapToGrid` geometry geomA float size geometry `ST_SnapToGrid` geometry geomA geometry pointOrigin float sizeX float sizeY float sizeZ float sizeM

### Description

Variant 1,2,3: Snap all points of the input geometry to the grid defined by its origin and cell size. Remove consecutive points falling on the same cell, eventually returning NULL if output points are not enough to define a geometry of the given type. Collapsed geometries in a collection are stripped from it.

Variant 4: Introduced 1.1.0 - Snap all points of the input geometry to the grid defined by its origin (the second argument, must be a point) and cell sizes. Specify 0 as size for any dimension you don't want to snap to a grid.

The returned geometry might loose its simplicity (see ).

Before release 1.1.0 this function always returned a 2d geometry. Starting at 1.1.0 the returned geometry will have same dimensionality as the input one with higher dimension values untouched. Use the version taking a second geometry argument to define all grid dimensions.

Availability: 1.0.0RC1

Availability: 1.1.0 - Z and M support

&Z_support;

### Examples

    --Snap your geometries to a precision grid of 10^-3
    UPDATE mytable
       SET the_geom = ST_SnapToGrid(the_geom, 0.001);

    SELECT ST_AsText(ST_SnapToGrid(
    			ST_GeomFromText('LINESTRING(1.1115678 2.123, 4.111111 3.2374897, 4.11112 3.23748667)'),
    			0.001)
    		);
    			  st_astext
    -------------------------------------
     LINESTRING(1.112 2.123,4.111 3.237)
     --Snap a 4d geometry
    SELECT ST_AsEWKT(ST_SnapToGrid(
    	ST_GeomFromEWKT('LINESTRING(-1.1115678 2.123 2.3456 1.11111,
    		4.111111 3.2374897 3.1234 1.1111, -1.11111112 2.123 2.3456 1.1111112)'),
     ST_GeomFromEWKT('POINT(1.12 2.22 3.2 4.4444)'),
     0.1, 0.1, 0.1, 0.01) );
    								  st_asewkt
    ------------------------------------------------------------------------------
     LINESTRING(-1.08 2.12 2.3 1.1144,4.12 3.22 3.1 1.1144,-1.08 2.12 2.3 1.1144)

    --With a 4d geometry - the ST_SnapToGrid(geom,size) only touches x and y coords but keeps m and z the same
    SELECT ST_AsEWKT(ST_SnapToGrid(ST_GeomFromEWKT('LINESTRING(-1.1115678 2.123 3 2.3456,
    		4.111111 3.2374897 3.1234 1.1111)'),
    	   0.01)      );
    						st_asewkt
    ---------------------------------------------------------
     LINESTRING(-1.11 2.12 3 2.3456,4.11 3.24 3.1234 1.1111)

### See Also

, , , ,

ST_Transform Returns a new geometry with its coordinates transformed to the SRID referenced by the integer parameter.
geometry `ST_Transform` geometry g1 integer srid

### Description

Returns a new geometry with its coordinates transformed to spatial reference system referenced by the SRID integer parameter. The destination SRID must exist in the `SPATIAL_REF_SYS` table.

ST_Transform is often confused with ST_SetSRID(). ST_Transform actually changes the coordinates of a geometry from one spatial reference system to another, while ST_SetSRID() simply changes the SRID identifier of the geometry

Requires PostGIS be compiled with Proj support. Use to confirm you have proj support compiled in.

If using more than one transformation, it is useful to have a functional index on the commonly used transformations to take advantage of index usage.

Prior to 1.3.4, this function crashes if used with geometries that contain CURVES. This is fixed in 1.3.4+

&sfs_compliant;

&sqlmm_compliant; SQL-MM 3: 5.1.6

&curve_support;

### Examples

Change Mass state plane US feet geometry to WGS 84 long lat

    SELECT ST_AsText(ST_Transform(ST_GeomFromText('POLYGON((743238 2967416,743238 2967450,
    	743265 2967450,743265.625 2967416,743238 2967416))',2249),4326)) As wgs_geom;

     wgs_geom
    ---------------------------
     POLYGON((-71.1776848522251 42.3902896512902,-71.1776843766326 42.3903829478009,
    -71.1775844305465 42.3903826677917,-71.1775825927231 42.3902893647987,-71.177684
    8522251 42.3902896512902));
    (1 row)

    --3D Circular String example
    SELECT ST_AsEWKT(ST_Transform(ST_GeomFromEWKT('SRID=2249;CIRCULARSTRING(743238 2967416 1,743238 2967450 2,743265 2967450 3,743265.625 2967416 3,743238 2967416 4)'),4326));

    				 st_asewkt
    --------------------------------------------------------------------------------------
     SRID=4326;CIRCULARSTRING(-71.1776848522251 42.3902896512902 1,-71.1776843766326 42.3903829478009 2,
     -71.1775844305465 42.3903826677917 3,
     -71.1775825927231 42.3902893647987 3,-71.1776848522251 42.3902896512902 4)

Example of creating a partial functional index. For tables where you are not sure all the geometries will be filled in, its best to use a partial index that leaves out null geometries which will both conserve space and make your index smaller and more efficient.

    CREATE INDEX idx_the_geom_26986_parcels
      ON parcels
      USING gist
      (ST_Transform(the_geom, 26986))
      WHERE the_geom IS NOT NULL;

### Configuring transformation behaviour

Sometimes coordinate transformation involving a grid-shift can fail, for example if PROJ.4 has not been built with grid-shift files or the coordinate does not lie within the range for which the grid shift is defined. By default, PostGIS will throw an error if a grid shift file is not present, but this behaviour can be configured on a per-SRID basis by altering the proj4text value within the spatial_ref_sys table.

For example, the proj4text parameter +datum=NAD87 is a shorthand form for the following +nadgrids parameter:

    +nadgrids=@conus,@alaska,@ntv2_0.gsb,@ntv1_can.dat

The @ prefix means no error is reported if the files are not present, but if the end of the list is reached with no file having been appropriate (ie. found and overlapping) then an error is issued.

If, conversely, you wanted to ensure that at least the standard files were present, but that if all files were scanned without a hit a null transformation is applied you could use:

    +nadgrids=@conus,@alaska,@ntv2_0.gsb,@ntv1_can.dat,null

The null grid shift file is a valid grid shift file covering the whole world and applying no shift. So for a complete example, if you wanted to alter PostGIS so that transformations to SRID 4267 that didn't lie within the correct range did not throw an ERROR, you would use the following:

    UPDATE spatial_ref_sys SET proj4text = '+proj=longlat +ellps=clrk66 +nadgrids=@conus,@alaska,@ntv2_0.gsb,@ntv1_can.dat,null +no_defs' WHERE srid = 4267;

### See Also

, , ,

ST_Translate Translates the geometry to a new location using the numeric parameters as offsets. Ie: ST_Translate(geom, X, Y) or ST_Translate(geom, X, Y,Z).
geometry `ST_Translate` geometry g1 float deltax float deltay geometry `ST_Translate` geometry g1 float deltax float deltay float deltaz

### Description

Returns a new geometry whose coordinates are translated delta x,delta y,delta z units. Units are based on the units defined in spatial reference (SRID) for this geometry.

Prior to 1.3.4, this function crashes if used with geometries that contain CURVES. This is fixed in 1.3.4+

Availability: 1.2.2

&Z_support;

&curve_support;

### Examples

Move a point 1 degree longitude

    	SELECT ST_AsText(ST_Translate(ST_GeomFromText('POINT(-71.01 42.37)',4326),1,0)) As wgs_transgeomtxt;

    	wgs_transgeomtxt
    	---------------------
    	POINT(-70.01 42.37)

Move a linestring 1 degree longitude and 1/2 degree latitude

    SELECT ST_AsText(ST_Translate(ST_GeomFromText('LINESTRING(-71.01 42.37,-71.11 42.38)',4326),1,0.5)) As wgs_transgeomtxt;
    		   wgs_transgeomtxt
    	---------------------------------------
    	LINESTRING(-70.01 42.87,-70.11 42.88)

Move a 3d point

    SELECT ST_AsEWKT(ST_Translate(CAST('POINT(0 0 0)' As geometry), 5, 12,3));
    	st_asewkt
    	---------
    	POINT(5 12 3)

Move a curve and a point

    SELECT ST_AsText(ST_Translate(ST_Collect('CURVEPOLYGON(CIRCULARSTRING(4 3,3.12 0.878,1 0,-1.121 5.1213,6 7, 8 9,4 3))','POINT(1 3)'),1,2));
    														 st_astext
    ------------------------------------------------------------------------------------------------------------
     GEOMETRYCOLLECTION(CURVEPOLYGON(CIRCULARSTRING(5 5,4.12 2.878,2 2,-0.121 7.1213,7 9,9 11,5 5)),POINT(2 5))

### See Also

, ,

ST_TransScale Translates the geometry using the deltaX and deltaY args, then scales it using the XFactor, YFactor args, working in 2D only.
geometry `ST_TransScale` geometry geomA float deltaX float deltaY float XFactor float YFactor

### Description

Translates the geometry using the deltaX and deltaY args, then scales it using the XFactor, YFactor args, working in 2D only.

`ST_TransScale(geomA, deltaX, deltaY, XFactor, YFactor)` is short-hand for `ST_Affine(geomA, XFactor, 0, 0, 0, YFactor, 0, 0, 0, 1, deltaX*XFactor, deltaY*YFactor, 0)`.

Prior to 1.3.4, this function crashes if used with geometries that contain CURVES. This is fixed in 1.3.4+

Availability: 1.1.0.

&Z_support;

&curve_support;

### Examples

    SELECT ST_AsEWKT(ST_TransScale(ST_GeomFromEWKT('LINESTRING(1 2 3, 1 1 1)'), 0.5, 1, 1, 2));
    		  st_asewkt
    -----------------------------
     LINESTRING(1.5 6 3,1.5 4 1)

    --Buffer a point to get an approximation of a circle, convert to curve and then translate 1,2 and scale it 3,4
      SELECT ST_AsText(ST_Transscale(ST_LineToCurve(ST_Buffer('POINT(234 567)', 3)),1,2,3,4));
    														  st_astext
    ------------------------------------------------------------------------------------------------------------------------------
     CURVEPOLYGON(CIRCULARSTRING(714 2276,711.363961030679 2267.51471862576,705 2264,698.636038969321 2284.48528137424,714 2276))

### See Also

,