Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
The 'actuate' attribute is used to communicate the desired timing
of traversal from the starting resource to the ending resource;
it's value should be treated as follows:
onLoad - traverse to the ending resource immediately on loading
the starting resource
onRequest - traverse from the starting resource to the ending
resource only on a post-loading event triggered for
this purpose
other - behavior is unconstrained; examine other markup in link
for hints
none - behavior is unconstrained
The 'show' attribute is used to communicate the desired presentation
of the ending resource on traversal from the starting resource; it's
value should be treated as follows:
new - load ending resource in a new window, frame, pane, or other
presentation context
replace - load the resource in the same window, frame, pane, or
other presentation context
embed - load ending resource in place of the presentation of the
starting resource
other - behavior is unconstrained; examine other markup in the
link for hints
none - behavior is unconstrained
<element name="offsetBase" type="gml:CurvePropertyType"><annotation><documentation>offsetBase is a reference to thecurve from which this curve is define as an offset.</documentation></annotation></element>
distance is the distance at which the
offset curve is generated from the basis curve. In 2D systems, positive distances
are to be to the left of the basis curve, and the negative distances are to be to the
right of the basis curve.
<element name="distance" type="gml:LengthType"><annotation><documentation>distance is the distance at which the offset curve is generated from the basis curve. In 2D systems, positive distances are to be to the left of the basis curve, and the negative distances are to be to the right of the basis curve.</documentation></annotation></element>
refDistance is used to define the vector
direction of the offset curve from the basis curve. It can
be omitted in the 2D case, where the distance can be
positive or negative. In that case, distance defines left
side (positive distance) or right side (negative distance)
with respect to the tangent to the basis curve.
In 3D the basis curve shall have a well defined tangent
direction for every point. The offset curve at any point
in 3D, the basis curve shall have a well-defined tangent
direction for every point. The offset curve at any point
(parameter) on the basis curve c is in the direction
- - - -
s = v x t where v = c.refDirection()
and
-
t = c.tangent()
-
For the offset direction to be well-defined, v shall not
on any point of the curve be in the same, or opposite,
direction as
-
t.
The default value of the refDirection shall be the local
co-ordinate axis vector for elevation, which indicates up for
the curve in a geographic sense.
NOTE! If the refDirection is the positive tangent to the
local elevation axis ("points upward"), then the offset
vector points to the left of the curve when viewed from
above.
Ordered list of labels for all the axes of this CRS. The gml:axisAbbrev value should be used for these axis
labels, after spaces and forbiddden characters are removed. When the srsName attribute is included, this attribute is
optional.
When the srsName attribute is omitted, this attribute shall also be omitted.
The "srsDimension" is the length of coordinate sequence (the number of entries in the list). This dimension is
specified by the coordinate reference system. When the srsName attribute is omitted, this attribute shall be omitted.
In general this reference points to a CRS instance of gml:CoordinateReferenceSystemType
(see coordinateReferenceSystems.xsd). For well known references it is not required that the CRS description exists at
the
location the URI points to. If no srsName attribute is given, the CRS must be specified as part of the larger context
this
geometry element is part of, e.g. a geometric element like point, curve, etc. It is expected that this attribute will
be specified
at the direct position level only in rare cases.
Ordered list of unit of measure (uom) labels for all the axes of this CRS. The value of the string in the
gml:catalogSymbol should be used for this uom labels, after spaces and forbiddden characters are removed. When the
axisLabels attribute is included, this attribute shall also be included. When the axisLabels attribute is omitted, this
attribute
shall also be omitted.
Source
<element name="refDirection" type="gml:VectorType" minOccurs="0"><annotation><documentation>refDistance is used to define the vector direction of the offset curve from the basis curve. It can be omitted in the 2D case, where the distance can be positive or negative. In that case, distance defines left side (positive distance) or right side (negative distance) with respect to the tangent to the basis curve. In 3D the basis curve shall have a well defined tangent direction for every point. The offset curve at any point in 3D, the basis curve shall have a well-defined tangent direction for every point. The offset curve at any point (parameter) on the basis curve c is in the direction - - - - s = v x t where v = c.refDirection() and - t = c.tangent() - For the offset direction to be well-defined, v shall not on any point of the curve be in the same, or opposite, direction as - t. The default value of the refDirection shall be the local co-ordinate axis vector for elevation, which indicates up for the curve in a geographic sense. NOTE! If the refDirection is the positive tangent to the local elevation axis ("points upward"), then the offset vector points to the left of the curve when viewed from above.</documentation></annotation></element>
An offset curve is a curve at a constant
distance from the basis curve. They can be useful as a cheap
and simple alternative to constructing curves that are offsets
by definition.
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="OffsetCurveType"><annotation><documentation>An offset curve is a curve at a constant distance from the basis curve. They can be useful as a cheap and simple alternative to constructing curves that are offsets by definition.</documentation></annotation><complexContent><extension base="gml:AbstractCurveSegmentType"><sequence><element name="offsetBase" type="gml:CurvePropertyType"><annotation><documentation>offsetBase is a reference to thecurve from which this curve is define as an offset.</documentation></annotation></element><element name="distance" type="gml:LengthType"><annotation><documentation>distance is the distance at which the offset curve is generated from the basis curve. In 2D systems, positive distances are to be to the left of the basis curve, and the negative distances are to be to the right of the basis curve.</documentation></annotation></element><element name="refDirection" type="gml:VectorType" minOccurs="0"><annotation><documentation>refDistance is used to define the vector direction of the offset curve from the basis curve. It can be omitted in the 2D case, where the distance can be positive or negative. In that case, distance defines left side (positive distance) or right side (negative distance) with respect to the tangent to the basis curve. In 3D the basis curve shall have a well defined tangent direction for every point. The offset curve at any point in 3D, the basis curve shall have a well-defined tangent direction for every point. The offset curve at any point (parameter) on the basis curve c is in the direction - - - - s = v x t where v = c.refDirection() and - t = c.tangent() - For the offset direction to be well-defined, v shall not on any point of the curve be in the same, or opposite, direction as - t. The default value of the refDirection shall be the local co-ordinate axis vector for elevation, which indicates up for the curve in a geographic sense. NOTE! If the refDirection is the positive tangent to the local elevation axis ("points upward"), then the offset vector points to the left of the curve when viewed from above.</documentation></annotation></element></sequence></extension></complexContent></complexType>
