gml:BSpline

A B-Spline is a piecewise parametric polynomial or rational curve described in terms of control points and basis functions as specified in ISO 19107:2003, 6.4.30. Therefore, interpolation may be either "polynomialSpline" or "rationalSpline" depending on the interpolation type; default is "polynomialSpline".
degree shall be the degree of the polynomial used for interpolation in this spline.
knot shall be the sequence of distinct knots used to define the spline basis functions (see ISO 19107:2003, 6.4.26.2).
The attribute isPolynomial shall be set to "true" if this is a polynomial spline (see ISO 19107:2003, 6.4.30.5).
The attribute knotType shall provide the type of knot distribution used in defining this spline (see ISO 19107:2003, 6.4.30.4).
The content model follows the general pattern for the encoding of curve segments.

Element information

Namespace: http://www.opengis.net/gml/3.2

Schema document: external/ogc/gml/3.2.1/geometryPrimitives.xsd

Type: gml:BSplineType

Properties: Global, Qualified

Content

Choice [1..1]
- Choice [0..*]
  - gml:pos
  - gml:pointPropertyThis property element either references a point via the XLink-attributes or contains the point element. pointProperty is the predefined property which may be used by GML Application Schemas whenever a GML feature has a property with a value that is substitutable for Point.
  - gml:pointRep
- gml:posList
- gml:coordinates
gml:degree [1..1]
gml:knot [2..*]

Attributes

Name	Occ	Type	Notes
numDerivativesAtStart	[0..1]	xsd:integer	Default value is "0". from type gml:AbstractCurveSegmentType
numDerivativesAtEnd	[0..1]	xsd:integer	Default value is "0". from type gml:AbstractCurveSegmentType
numDerivativeInterior	[0..1]	xsd:integer	Default value is "0". from type gml:AbstractCurveSegmentType
interpolation	[0..1]	gml:CurveInterpolationType	Default value is "polynomialSpline".
isPolynomial	[0..1]	xsd:boolean
knotType	[0..1]	gml:KnotTypesType

Used in

Type gml:ArrayAssociationType (Element gml:members)
Type gml:CurveSegmentArrayPropertyType (Element gml:segments)

Substitution hierarchy

gml:AbstractObject
- can be substituted with gml:AbstractCurveSegment
  - can be substituted with gml:BSpline
    - can be substituted with gml:Bezier

Sample instance

<gml:BSpline>
   <gml:pos>1.0 1.0</gml:pos>
   <gml:degree>1</gml:degree>
   <gml:knot>
      <gml:Knot>
         <gml:value>1.0</gml:value>
         <gml:multiplicity>1</gml:multiplicity>
         <gml:weight>1.0</gml:weight>
      </gml:Knot>
   </gml:knot>
</gml:BSpline>