constructors
CORE
This module contains functions that create new geographies from coordinates or already existing geographies.
ST_BEZIERSPLINE(linestring [, resolution] [, sharpness])
Description
Takes a line and returns a curved version of it by applying a Bezier spline algorithm. Note that the resulting geography will be a LineString with additional points inserted.
geog
:GEOMETRY
input LineString.resolution
(optional):INT
total time in milliseconds assigned to the line. Tthe default value is10000
. Internal curve vertices are generated in 10 ms increments, so the maximum number of resulting points will beresolution/10
(close points may be merged resulting in less points). A higher number will increase the accuracy of the result but will increase the computation time and number of points.sharpness
(optional):FLOAT8
a measure of how curvy the path should be between splines. If not specified, the default value of0.85
will be used.
Return type
VARCHAR(MAX)
Examples
1
SELECT carto.ST_BEZIERSPLINE(
2
ST_GEOMFROMTEXT(
3
'LINESTRING (-76.091308 18.427501,-76.695556 18.729501,-76.552734 19.40443,-74.61914 19.134789,-73.652343 20.07657,-73.157958 20.210656)'
4
)
5
);
6
-- {"type": "LineString", "coordinates": [[-76.091308, 18.427501], [-76.09134585033101, 18.427508082543092], ...
1
SELECT carto.ST_BEZIERSPLINE(
2
ST_GEOMFROMTEXT(
3
'LINESTRING (-76.091308 18.427501,-76.695556 18.729501,-76.552734 19.40443,-74.61914 19.134789,-73.652343 20.07657,-73.157958 20.210656)'
4
),
5
10000
6
);
7
-- {"type": "LineString", "coordinates": [[-76.091308, 18.427501], [-76.09134585033101, 18.427508082543092], ...
1
SELECT carto.ST_BEZIERSPLINE(
2
ST_GEOMFROMTEXT(
3
'LINESTRING (-76.091308 18.427501,-76.695556 18.729501,-76.552734 19.40443,-74.61914 19.134789,-73.652343 20.07657,-73.157958 20.210656)'
4
),
5
10000,
6
0.9
7
);
8
-- {"type": "LineString", "coordinates": [[-76.091308, 18.427501], [-76.09134541990707, 18.42750717125151], ...
ST_MAKEELLIPSE(center, xSemiAxis, ySemiAxis [, angle] [, units] [, steps])
Description
Takes a Point as input and calculates the ellipse polygon given two semi-axes expressed in variable units and steps for precision.
center
:GEOMETRY
center point.xSemiAxis
:FLOAT8
semi (major) axis of the ellipse along the x-axis.ySemiAxis
:FLOAT8
semi (minor) axis of the ellipse along the y-axis.angle
(optional):FLOAT8
angle of rotation (along the vertical axis), from North in decimal degrees, negative clockwise. If not specified, the default value of0
will be used.units
(optional):VARCHAR(10)
units of length. The supported options are: miles, kilometers, meters, and degrees. If not specified,kilometers
will be used.steps
(optional):INT
number of steps. If not specified, the default value of64
will be used.
Return type
VARCHAR(MAX)
Examples
1
SELECT carto.ST_MAKEELLIPSE(ST_POINT(-73.9385,40.6643), 5, 3);
2
-- {"type": "Polygon", "coordinates": [[[-73.87922034627275, 40.6643], [-73.88056149301754, 40.67000644486112], ...
1
SELECT carto.ST_MAKEELLIPSE(ST_POINT(-73.9385,40.6643), 5, 3, -30);
2
-- {"type": "Polygon", "coordinates": [[[-73.88703173808466, 40.68643711664552], [-73.89195608204625, 40.69086946050236], ...
1
SELECT carto.ST_MAKEELLIPSE(ST_Point(-73.9385,40.6643), 5, 3, -30, 'miles');
2
-- {"type": "Polygon", "coordinates": [[[-73.85566162723387, 40.69992623586439], [-73.86358797643032, 40.707058494394765], ...
1
SELECT carto.ST_MAKEELLIPSE(ST_Point(-73.9385,40.6643), 5, 3, -30, 'miles', 80);
2
-- {"type": "Polygon", "coordinates": [[[-73.8557003345262, 40.70003619338248], [-73.86178810440265, 40.705912341919415], ...
ST_MAKEENVELOPE(xmin, ymin, xmax, ymax)
Description Creates a rectangular Polygon from the minimum and maximum values for X and Y.
xmin
:FLOAT8
minimum value for X.ymin
:FLOAT8
minimum value for Y.xmax
:FLOAT8
maximum value for X.ymax
:FLOAT8
maximum value for Y.
Return type
GEOMETRY
Example
1
SELECT carto.ST_MAKEENVELOPE(0, 0, 1, 1);
2
-- POLYGON ((0 0, 0 1, 1 1, 1 0, 0 0))
ST_TILEENVELOPE(zoomLevel, xTile, yTile)
Description Returns the boundary polygon of a tile given its zoom level and its X and Y indices.
zoomLevel
:INT
zoom level of the tile.xTile
:INT
X index of the tile.yTile
:INT
Y index of the tile.
Return type
GEOMETRY
Example
1
SELECT carto.ST_TILEENVELOPE(10, 384, 368);
2
-- {'type': 'Polygon', 'coordinates': [[[-45.0, 44.84029065139799], [-45.0, 45.089035564831015], ...
Last modified 6mo ago