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. Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced. 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+ &P_support; &T_support; &Z_support; &curve_support; Examples --Rotate a 3d line 180 degrees about the z axis. Note this is long-hand for doing ST_Rotate(); 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_Rotate(the_geom, pi())) As using_rotate FROM (SELECT ST_GeomFromEWKT('LINESTRING(1 2 3, 1 4 3)') As the_geom) As foo; using_affine | using_rotate -----------------------------+----------------------------- 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_Force2D Forces the geometries into a "2-dimensional mode" so that all output representations will only have the X and Y coordinates. geometry ST_Force2D 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). Enhanced: 2.0.0 support for Polyhedral surfaces was introduced. Changed: 2.1.0. Up to 2.0.x this was called ST_Force_2D. &curve_support; &P_support; &Z_support; Examples SELECT ST_AsEWKT(ST_Force2D(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_Force2D('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_Force3D Forces the geometries into XYZ mode. This is an alias for ST_Force3DZ. geometry ST_Force3D 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. Enhanced: 2.0.0 support for Polyhedral surfaces was introduced. Changed: 2.1.0. Up to 2.0.x this was called ST_Force_3D. &P_support; &curve_support; &Z_support; Examples --Nothing happens to an already 3D geometry SELECT ST_AsEWKT(ST_Force3D(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_Force3D('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_Force3DZ Forces the geometries into XYZ mode. This is a synonym for ST_Force3D. geometry ST_Force3DZ geometry geomA Description Forces the geometries into XYZ mode. This is a synonym for ST_Force3DZ. If a geometry has no Z component, then a 0 Z coordinate is tacked on. Enhanced: 2.0.0 support for Polyhedral surfaces was introduced. Changed: 2.1.0. Up to 2.0.x this was called ST_Force_3DZ. &P_support; &Z_support; &curve_support; Examples --Nothing happens to an already 3D geometry SELECT ST_AsEWKT(ST_Force3DZ(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_Force3DZ('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_Force3DM Forces the geometries into XYM mode. geometry ST_Force3DM 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 Changed: 2.1.0. Up to 2.0.x this was called ST_Force_3DM. &curve_support; Examples --Nothing happens to an already 3D geometry SELECT ST_AsEWKT(ST_Force3DM(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_Force3DM('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_Force4D Forces the geometries into XYZM mode. geometry ST_Force4D geometry geomA Description Forces the geometries into XYZM mode. 0 is tacked on for missing Z and M dimensions. Changed: 2.1.0. Up to 2.0.x this was called ST_Force_4D. &Z_support; &curve_support; Examples --Nothing happens to an already 3D geometry SELECT ST_AsEWKT(ST_Force4D(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_Force4D('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_ForceCollection Converts the geometry into a GEOMETRYCOLLECTION. geometry ST_ForceCollection geometry geomA Description Converts the geometry into a GEOMETRYCOLLECTION. This is useful for simplifying the WKB representation. Enhanced: 2.0.0 support for Polyhedral surfaces was introduced. Availability: 1.2.2, prior to 1.3.4 this function will crash with Curves. This is fixed in 1.3.4+ Changed: 2.1.0. Up to 2.0.x this was called ST_Force_Collection. &P_support; &Z_support; &curve_support; Examples SELECT ST_AsEWKT(ST_ForceCollection('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_ForceCollection('CIRCULARSTRING(220227 150406,2220227 150407,220227 150406)')); st_astext -------------------------------------------------------------------------------- GEOMETRYCOLLECTION(CIRCULARSTRING(220227 150406,2220227 150407,220227 150406)) (1 row) -- POLYHEDRAL example -- SELECT ST_AsEWKT(ST_ForceCollection('POLYHEDRALSURFACE(((0 0 0,0 0 1,0 1 1,0 1 0,0 0 0)), ((0 0 0,0 1 0,1 1 0,1 0 0,0 0 0)), ((0 0 0,1 0 0,1 0 1,0 0 1,0 0 0)), ((1 1 0,1 1 1,1 0 1,1 0 0,1 1 0)), ((0 1 0,0 1 1,1 1 1,1 1 0,0 1 0)), ((0 0 1,1 0 1,1 1 1,0 1 1,0 0 1)))')) st_asewkt ---------------------------------------------------------------------------------- GEOMETRYCOLLECTION( POLYGON((0 0 0,0 0 1,0 1 1,0 1 0,0 0 0)), POLYGON((0 0 0,0 1 0,1 1 0,1 0 0,0 0 0)), POLYGON((0 0 0,1 0 0,1 0 1,0 0 1,0 0 0)), POLYGON((1 1 0,1 1 1,1 0 1,1 0 0,1 1 0)), POLYGON((0 1 0,0 1 1,1 1 1,1 1 0,0 1 0)), POLYGON((0 0 1,1 0 1,1 1 1,0 1 1,0 0 1)) ) See Also , , , , ST_ForceSFS Forces the geometries to use SFS 1.1 geometry types only. geometry ST_ForceSFS geometry geomA geometry ST_ForceSFS geometry geomA text version Description &P_support; &T_support; &curve_support; &Z_support; 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. Enhanced: 2.0.0 support for Polyhedral surfaces was introduced. &Z_support; &P_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 (multi)geometry, returns a (multi)geometry consisting only of elements of the specified type. geometry ST_CollectionExtract geometry collection integer type Description Given a (multi)geometry, returns a (multi)geometry consisting only of elements 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 geometry will be returned. Only points, lines and polygons are supported. Type numbers are 1 == POINT, 2 == LINESTRING, 3 == POLYGON. Availability: 1.5.0 Prior to 1.5.3 this function returned non-collection inputs untouched, no matter type. In 1.5.3 non-matching single geometries result in a NULL return. In of 2.0.0 every case of missing match results in a typed EMPTY return. 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_CollectionHomogenize Given a geometry collection, returns the "simplest" representation of the contents. geometry ST_CollectionHomogenize geometry collection Description Given a geometry collection, returns the "simplest" representation of the contents. Singletons will be returned as singletons. Collections that are homogeneous will be returned as the appropriate multi-type. Availability: 2.0.0 Examples SELECT ST_AsText(ST_CollectionHomogenize('GEOMETRYCOLLECTION(POINT(0 0))')); st_astext ------------ POINT(0 0) (1 row) SELECT ST_AsText(ST_CollectionHomogenize('GEOMETRYCOLLECTION(POINT(0 0),POINT(1 1))')); st_astext --------------------- MULTIPOINT(0 0,1 1) (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 Rotate a geometry rotRadians counter-clockwise about an origin. geometry ST_Rotate geometry geomA float rotRadians geometry ST_Rotate geometry geomA float rotRadians float x0 float y0 geometry ST_Rotate geometry geomA float rotRadians geometry pointOrigin Description Rotates geometry rotRadians counter-clockwise about the origin. The rotation origin can be specified either as a POINT geometry, or as x and y coordinates. If the origin is not specified, the geometry is rotated about POINT(0 0). Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced. Enhanced: 2.0.0 additional parameters for specifying the origin of rotation were added. Availability: 1.1.2. Name changed from Rotate to ST_Rotate in 1.2.2 &Z_support; &curve_support; &P_support; &T_support; Examples --Rotate 180 degrees SELECT ST_AsEWKT(ST_Rotate('LINESTRING (50 160, 50 50, 100 50)', pi())); st_asewkt --------------------------------------- LINESTRING(-50 -160,-50 -50,-100 -50) (1 row) --Rotate 30 degrees counter-clockwise at x=50, y=160 SELECT ST_AsEWKT(ST_Rotate('LINESTRING (50 160, 50 50, 100 50)', pi()/6, 50, 160)); st_asewkt --------------------------------------------------------------------------- LINESTRING(50 160,105 64.7372055837117,148.301270189222 89.7372055837117) (1 row) --Rotate 60 degrees clockwise from centroid SELECT ST_AsEWKT(ST_Rotate(geom, -pi()/3, ST_Centroid(geom))) FROM (SELECT 'LINESTRING (50 160, 50 50, 100 50)'::geometry AS geom) AS foo; st_asewkt -------------------------------------------------------------- LINESTRING(116.4225 130.6721,21.1597 75.6721,46.1597 32.3708) (1 row) 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)`. Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced. Availability: 1.1.2. Name changed from RotateX to ST_RotateX in 1.2.2 &P_support; &Z_support; &T_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 Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced. &P_support; &Z_support; &T_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 , , 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. This is a synonym for ST_Rotate `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)`. Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced. 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; &P_support; &T_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 , , 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. Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced. &P_support; &Z_support; &curve_support; &T_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/geography having no segment longer than the given distance. Distance computation is performed in 2d only. For geometry, length units are in units of spatial reference. For geography, units are in meters. geometry ST_Segmentize geometry geom float max_segment_length geometry ST_Segmentize geography geog float max_segment_length Description Returns a modified geometry having no segment longer than the given max_segment_length. Distance computation is performed in 2d only. For geometry, length units are in units of spatial reference. For geography, units are in meters. Availability: 1.2.2 Enhanced: 2.1.0 support for geography was introduced. Changed: 2.1.0 As a result of the introduction of geography support: The construct `SELECT ST_Segmentize('LINESTRING(1 2, 3 4)',0.5);` will result in ambiguous function error. You need to have properly typed object e.g. a geometry/geography column, use ST_GeomFromText, ST_GeogFromText or `SELECT ST_Segmentize('LINESTRING(1 2, 3 4)'::geometry,0.5);` 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 a regular grid. 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. Useful for reducing precision. 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_Snap Snap segments and vertices of input geometry to vertices of a reference geometry. geometry ST_Snap geometry input geometry reference float tolerance Description Snaps the vertices and segments of a geometry another Geometry's vertices. A snap distance tolerance is used to control where snapping is performed. Snapping one geometry to another can improve robustness for overlay operations by eliminating nearly-coincident edges (which cause problems during noding and intersection calculation). Too much snapping can result in invalid topology being created, so the number and location of snapped vertices is decided using heuristics to determine when it is safe to snap. This can result in some potential snaps being omitted, however. The returned geometry might loose its simplicity (see ) and validity (see ). Availability: 2.0.0 requires GEOS >= 3.3.0. Examples A multipolygon shown with a linestring (before any snapping) A multipolygon snapped to linestring to tolerance: 1.01 of distance. The new multipolygon is shown with reference linestring SELECT ST_AsText(ST_Snap(poly,line, ST_Distance(poly,line)*1.01)) AS polysnapped FROM (SELECT ST_GeomFromText('MULTIPOLYGON( ((26 125, 26 200, 126 200, 126 125, 26 125 ), ( 51 150, 101 150, 76 175, 51 150 )), (( 151 100, 151 200, 176 175, 151 100 )))') As poly, ST_GeomFromText('LINESTRING (5 107, 54 84, 101 100)') As line ) As foo; polysnapped --------------------------------------------------------------------- MULTIPOLYGON(((26 125,26 200,126 200,126 125,101 100,26 125), (51 150,101 150,76 175,51 150)),((151 100,151 200,176 175,151 100))) A multipolygon snapped to linestring to tolerance: 1.25 of distance. The new multipolygon is shown with reference linestring SELECT ST_AsText( ST_Snap(poly,line, ST_Distance(poly,line)*1.25) ) AS polysnapped FROM (SELECT ST_GeomFromText('MULTIPOLYGON( (( 26 125, 26 200, 126 200, 126 125, 26 125 ), ( 51 150, 101 150, 76 175, 51 150 )), (( 151 100, 151 200, 176 175, 151 100 )))') As poly, ST_GeomFromText('LINESTRING (5 107, 54 84, 101 100)') As line ) As foo; polysnapped --------------------------------------------------------------------- MULTIPOLYGON(((5 107,26 200,126 200,126 125,101 100,54 84,5 107), (51 150,101 150,76 175,51 150)),((151 100,151 200,176 175,151 100))) The linestring snapped to the original multipolygon at tolerance 1.01 of distance. The new linestring is shown with reference multipolygon SELECT ST_AsText( ST_Snap(line, poly, ST_Distance(poly,line)*1.01) ) AS linesnapped FROM (SELECT ST_GeomFromText('MULTIPOLYGON( ((26 125, 26 200, 126 200, 126 125, 26 125), (51 150, 101 150, 76 175, 51 150 )), ((151 100, 151 200, 176 175, 151 100)))') As poly, ST_GeomFromText('LINESTRING (5 107, 54 84, 101 100)') As line ) As foo; linesnapped ---------------------------------------- LINESTRING(5 107,26 125,54 84,101 100) The linestring snapped to the original multipolygon at tolerance 1.25 of distance. The new linestring is shown with reference multipolygon SELECT ST_AsText( ST_Snap(line, poly, ST_Distance(poly,line)*1.25) ) AS linesnapped FROM (SELECT ST_GeomFromText('MULTIPOLYGON( (( 26 125, 26 200, 126 200, 126 125, 26 125 ), (51 150, 101 150, 76 175, 51 150 )), ((151 100, 151 200, 176 175, 151 100 )))') As poly, ST_GeomFromText('LINESTRING (5 107, 54 84, 101 100)') As line ) As foo; linesnapped --------------------------------------- LINESTRING(26 125,54 84,101 100) 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+ Enhanced: 2.0.0 support for Polyhedral surfaces was introduced. &sqlmm_compliant; SQL-MM 3: 5.1.6 &curve_support; &P_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 ,