Interpolate points on a LineString using ST_LineInterpolatePoints - PolarDB

Interpolates a point at one or more specified locations of a LineString object and returns the points.

Syntax

geometry  ST_LineInterpolatePoints(geometry  aLinestring, float8  aFraction, boolean  repeat);
geography ST_LineInterpolatePoints(geography aLinestring, float8  aFraction, boolean  repeat);

Parameters

Parameter	Type	Description
`aLinestring`	geometry / geography	The LineString to interpolate along.
`aFraction`	float8	The fraction based on which the point is interpolated into the line. Valid values: floating-point numbers in the range 0 to 1.
`repeat`	boolean	Specifies whether to generate points at every interval along the line. Default value: `true`. When set to `false`, at most one point is returned.

Usage notes

When repeat is true, the function places a point at every location that is represented as a fraction along the line.
If the result contains zero or one point, the return type is Point. If the result contains more than one point, the return type is MultiPoint.
3D geometries are supported. Z coordinates are preserved in the output.
M coordinates are supported.
For the geography overload, distances are calculated using spherical distance rather than planar distance.

Examples

Interpolate points every 20% along a line (geometry)

SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)', 0.20));

Result:

 MULTIPOINT(0 1,0 2,0 3,0 4,0 5)
(1 row)

Interpolate points every 20% along a line (geography)

SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)'::geography, 0.20));

Result:

 MULTIPOINT((0 1.00002443285827),(0 2.00004274948544),(0 3.00004884128919),(0 4.00003661494431),(0 5))

Return a single point with repeat set to false (geometry)

SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)', 0.20, false));

Result:

 POINT(0 1)
(1 row)

Return a single point with repeat set to false (geography)

SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)'::geography, 0.20, false));

Result:

 POINT(0 1.00002443285827)
(1 row)