Name
CG_NurbsCurveInterpolate — Creates an interpolating NURBS curve passing through all given data points
Synopsis
geometry CG_NurbsCurveInterpolate(geometry data_points, integer degree);
Description
Creates a NURBS curve that interpolates through all provided data points. The resulting curve passes exactly through each point in the input geometry.
Parameters:
-
data_points- A LINESTRING geometry containing the points to interpolate through. -
degree- Polynomial degree of the NURBS curve (typically 2 or 3).
Availability: 3.7.0 - requires SFCGAL >= 2.3.0.
This method needs SFCGAL backend.
This function supports 3d and will not drop the z-index.
Examples
Interpolate a degree-3 NURBS curve through four 2D points.
WITH data AS (
SELECT 'LINESTRING(0 0,2 5,5 3,8 1)'::geometry AS input_points
)
SELECT input_points AS input_points,
CG_NurbsCurveInterpolate(input_points, 3) AS interpolated_curve
FROM data;
LINESTRING(0 0,2 5,5 3,8 1) | NURBSCURVE(DEGREE 3, CONTROLPOINTS(NURBSPOINT(WEIGHTEDPOINT(0 0),WEIGHT 1), NURBSPOINT(WEIGHTEDPOINT(-0.43 10.29),WEIGHT 1), NURBSPOINT(WEIGHTEDPOINT(4.95 1.9),WEIGHT 1), NURBSPOINT(WEIGHTEDPOINT(8 1),WEIGHT 1)),KNOTS (KNOT(0,4), KNOT(1,4)))
Interpolate a 3D degree-3 NURBS curve through the documented control points.
WITH data AS (
SELECT 'LINESTRING Z (0 0 0,2 5 2,5 3 1,8 1 0)'::geometry AS input_points
)
SELECT input_points AS input_points,
CG_NurbsCurveInterpolate(input_points, 3) AS interpolated_curve
FROM data;
LINESTRING Z (0 0 0,2 5 2,5 3 1,8 1 0) | NURBSCURVE Z (DEGREE 3,CONTROLPOINTS Z (NURBSPOINT(WEIGHTEDPOINT Z (0 0 0),WEIGHT 1), NURBSPOINT(WEIGHTEDPOINT Z (-0.43 10.29 4.36),WEIGHT 1), NURBSPOINT(WEIGHTEDPOINT Z (4.95 1.9 0.54),WEIGHT 1), NURBSPOINT(WEIGHTEDPOINT Z (8 1 0),WEIGHT 1)),KNOTS (KNOT(0,4), KNOT(1,4)))