CurveType, Curve Geometric primitives 1-dimensional

Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 65 element ref=gml:baseCurve sequence attribute name=orientation type=gml:SignType default=+ extension complexContent complexType element name=baseCurve type=gml:CurvePropertyType element name=OrientableCurve type=gml:OrientableCurveType substitutionGroup=gml:AbstractCurve gml:OrientableCurve implements ISO 19107 GM_OrientableCurve see D.2.3.3 and ISO 19107:2003, 6.3.14. gml:OrientableCurve consists of a curve and an orientation. If the orientation is +, then the gml:OrientableCurve is identical to the gml:baseCurve. If the orientation is -, then the gml:OrientableCurve is related to another gml:AbstractCurve with a parameterization that reverses the sense of the curve traversal. The property gml:baseCurve references or contains the base curve, i.e. it either references the base curve via the XLink-attributes or contains the curve element. A curve element is any element which is substitutable for gml:AbstractCurve. The base curve has positive orientation. NOTE This definition allows for a nested structure, i.e. an gml:OrientableCurve may use another gml:OrientableCurve as its base curve. 10.4.7 Curve segments 10.4.7.1 AbstractCurveSegmentType, AbstractCurveSegment complexType name=AbstractCurveSegmentType abstract=true attribute name=numDerivativesAtStart type=integer default=0 attribute name=numDerivativesAtEnd type=integer default=0 attribute name=numDerivativeInterior type=integer default=0 complexType element name=AbstractCurveSegment type=gml:AbstractCurveSegmentType abstract=true substitutionGroup=gml:AbstractObject gml:AbstractCurveSegment implements ISO 19107 GM_CurveSegment see D.2.3.3 and ISO 19107:2003, 6.4.9. A curve segment defines a homogeneous segment of a curve. The attributes numDerivativesAtStart, numDerivativesAtEnd and numDerivativesInterior specify the type of continuity as specified in ISO 19107:2003, 6.4.9.3. The gml:AbstractCurveSegment element is the abstract head of the substitution group for all curve segment elements, i.e. continuous segments of the same interpolation mechanism. The encoding of the control points in a curve segment shall follow the pattern described in 10.1.4.4. All curve segments shall have an attribute interpolation with type gml:CurveInterpolationType specifying the curve interpolation mechanism used for this segment. This mechanism uses the control points and control parameters to determine the position of this curve segment.