A Geodesic consists of two distinctpositions joined by a geodesic curve. The control points ofa Geodesic shall lie on the geodesic between its startpoint and end points. Between these two points, a geodesiccurve defined from ellipsoid or geoid model used by theco-ordinate reference systems may be used to interpolateother positions. Any other point in the controlPoint arraymust fall on this geodesic.

The attribute "interpolation" specifies thecurve interpolation mechanism used for this segment. Thismechanism uses the control points and control parameters todetermine the position of this curve segment. For an GeodesicString the interpolation is fixed as "geodesic".

The attribute "numDerivativesInterior" specifies the type of continuity that is guaranteed interior to the curve. The default value of "0" means simple continuity, which is a mandatory minimum level of continuity. This level is referred to as "C 0 " in mathematical texts. A value of 1 means that the function and its first derivative are continuous at the appropriate end point: "C 1 " continuity. A value of "n" for any integer means the function and its first n derivatives are continuous: "C n " continuity.NOTE: Use of these values is only appropriate when the basic curve definition is an underdetermined system. For example, line string segments cannot support continuity above C 0 , since there is no spare control parameter to adjust the incoming angle at the end points of the segment. Spline functions on the other hand often have extra degrees of freedom on end segments that allow them to adjust the values of the derivatives to support C 1 or higher continuity.

The attribute "numDerivativesAtEnd" specifies the type of continuity between this curve segment and its successor. If this is the last curve segment in the curve, one of these values, as appropriate, is ignored. The default value of "0" means simple continuity, which is a mandatory minimum level of continuity. This level is referred to as "C 0 " in mathematical texts. A value of 1 means that the function and its first derivative are continuous at the appropriate end point: "C 1 " continuity. A value of "n" for any integer means the function and its first n derivatives are continuous: "C n " continuity.NOTE: Use of these values is only appropriate when the basic curve definition is an underdetermined system. For example, line string segments cannot support continuity above C 0 , since there is no spare control parameter to adjust the incoming angle at the end points of the segment. Spline functions on the other hand often have extra degrees of freedom on end segments that allow them to adjust the values of the derivatives to support C 1 or higher continuity.

The attribute "numDerivativesAtStart" specifies the type of continuity between this curve segment and its predecessor. If this is the first curve segment in the curve, one of these values, as appropriate, is ignored. The default value of "0" means simple continuity, which is a mandatory minimum level of continuity. This level is referred to as "C 0 " in mathematical texts. A value of 1 means that the function and its first derivative are continuous at the appropriate end point: "C 1 " continuity. A value of "n" for any integer means the function and its first n derivatives are continuous: "C n " continuity.NOTE: Use of these values is only appropriate when the basic curve definition is an underdetermined system. For example, line string segments cannot support continuity above C 0 , since there is no spare control parameter to adjust the incoming angle at the end points of the segment. Spline functions on the other hand often have extra degrees of freedom on end segments that allow them to adjust the values of the derivatives to support C 1 or higher continuity.

Source

<complexType name="GeodesicType"><annotation><documentation>A Geodesic consists of two distinct positions joined by a geodesic curve. The control points of a Geodesic shall lie on the geodesic between its start point and end points. Between these two points, a geodesic curve defined from ellipsoid or geoid model used by the co-ordinate reference systems may be used to interpolate other positions. Any other point in the controlPoint array must fall on this geodesic.</documentation></annotation><complexContent><extension base="gml:GeodesicStringType"/></complexContent></complexType>