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# transformations

CORE
This module contains functions that compute geometric constructions, or alter geometry size or shape.

### ST_CENTERMEAN

ST_CENTERMEAN(geom)
Description
Takes a Feature or FeatureCollection and returns the mean center (average of its vertices).
• `geom`: `GEOMETRY` for which to compute the mean center.
Return type
`GEOMETRY`
Example
1
SELECT carto.ST_CENTERMEAN(ST_GEOMFROMTEXT('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'));
2
-- POINT (25 27.5)

### ST_CENTERMEDIAN

ST_CENTERMEDIAN(geom)
Description
Takes a FeatureCollection of points and computes the median center. The median center is understood as the point that requires the least total travel from all other points.
• `geog`: `GEOMETRY` for which to compute the center.
Return type
`GEOMETRY`
Example
1
SELECT carto.ST_CENTERMEDIAN(ST_GEOMFROMTEXT('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'));
2
-- POINT (26.3841869726 19.0088147377)

### ST_CENTEROFMASS

ST_CENTEROFMASS(geom)
Description
Takes any Feature or a FeatureCollection and returns its center of mass. It is equivalent to `ST_CENTROID`.
• `geom`: `GEOMETRY` for which to compute the center of mass.
Return type
`GEOMETRY`
Example
1
SELECT carto.ST_CENTEROFMASS(ST_GEOMFROMTEXT('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'));
2
-- POINT (25.4545454545 26.9696969697)

### ST_CENTROID

ST_CENTROID(geom)
Description
Takes any Feature or a FeatureCollection as input and returns its centroid. It is equivalent to `ST_CENTEROFMASS`.
• `geom`: `GEOMETRY` for which to compute the centroid.
Return type
`GEOMETRY`
Example
1
SELECT carto.ST_CENTROID(ST_GEOMFROMTEXT('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'));
2
-- POINT (25.4545454545 26.9696969697)

### ST_DESTINATION

ST_DESTINATION(geom, distance, bearing, units)
Description
Takes a Point and calculates the location of a destination point given a distance in degrees, radians, miles, or kilometers; and a bearing in degrees. This uses the Haversine formula to account for global curvature.
• `geom`: `GEOMETRY` starting point.
• `distance`: `FLOAT8` distance from the origin point in the units specified.
• `bearing`: `FLOAT8` counter-clockwise angle from East, ranging from -180 to 180 (e.g. 0 is East, 90 is North, 180 is West, -90 is South).
• `units` (optional): `VARCHAR(15)` units of length. The supported options are: `miles`, `kilometers`, `degrees` or `radians`. If `NULL`the default value `kilometers` is used.
Return type
`GEOMETRY`
Examples
1
SELECT carto.ST_DESTINATION(ST_MakePoint(-3.70325,40.4167), 10, 45);
2
-- POINT (-3.61964617436 40.4802614598)
1
SELECT carto.ST_DESTINATION(ST_MakePoint(-3.70325,40.4167), 10, 45, 'miles');
2
-- POINT (-3.56862505482 40.5189626778)

### ST_GREATCIRCLE

ST_GREATCIRCLE(start_point, end_point, n_points)
Description
Calculates a great circle route as a LineString.
• `start_point`: `GEOMETRY` source point feature.
• `end_point`: `GEOMETRY` destination point feature.
• `n_points` (optional): `INT` number of points. Defaults to `100`.
Return type
`GEOMETRY`
Examples
1
SELECT carto.ST_GREATCIRCLE(ST_MAKEPOINT(-3.70325,40.4167), ST_MAKEPOINT(-73.9385,40.6643));
2
-- LINESTRING (-3.70325 40.4167, -4.32969777937 40.6355528695, ...
1
SELECT carto.ST_GREATCIRCLE(ST_MAKEPOINT(-3.70325,40.4167), ST_MAKEPOINT(-73.9385,40.6643), 20);
2
-- LINESTRING (-3.70325 40.4167, -7.01193184681 41.5188665219, ...