Property
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Description
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Class
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Superclass
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Subclass
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Definition
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An instance of this DRM class specifies where the given
<DRM Image> instance is located in the specified
SRF.
A <DRM Image Anchor> instance is used
in one of two ways:
- As a component of a <DRM Image> component of
a <DRM Image Library> instance.
In this case, the <DRM Image> instance is not tied to a
particular
<DRM Feature Representation> instance or
<DRM Geometry Representation> instance.
The <DRM Location> components of the
<DRM Image Anchor> instance
specify the positions of the corners of the
<DRM Image> instance in the specified SRF.
NOTE 1
If two georeferenced <DRM Image>
instances are to be placed exactly next to each other by means of
<DRM Image Anchor> components, the
<DRM Location> components of those
<DRM Image Anchor>
instances are exactly the same along the common edge.
- As a component of
a <DRM Image Mapping Function>
instance.
In this case, the <DRM Image Anchor> instance
defines how the associated <DRM Image> instance is to be
applied to the DRM object having the
<DRM Image Mapping Function>
instance as a component. The
srf_context_info of the
<DRM Image Anchor> instance shall match that
of the context in which the
<DRM Image Mapping Function>
instance is being applied.
<DRM Image Anchor> instances are used to
support spherical and cylindrical image projections for
<DRM Image Mapping Function>
instances. By specifying
anchor points that are not in the same plane, non-orthogonal
projection becomes possible.
NOTE 2
When an image mapping is applied to many
<DRM Polygon> instances using a single
<DRM Image Mapping Function> instance, a
continuous image results when displayed.
The srf_context_info field
specifies the SRF within which the
<DRM Image Anchor> instance is defined.
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Class diagram
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Figure 6.131 —
DRM_Image_Anchor
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Inherited field elements
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Field name
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Range
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Field data type
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None |
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Field elements
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Default field values
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Default field values for DRM_Image_Anchor
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Associated to (one-way) (inherited) |
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Associated to (one-way) |
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Associated by (one-way) (inherited) |
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Associated by (one-way) |
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Associated with (two-way) (inherited) |
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Associated with (two-way) |
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Composed of (two-way) (inherited) |
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Composed of (two-way) |
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Composed of (two-way metadata) (inherited) |
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Composed of (two-way metadata) |
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Component of (two-way) (inherited) |
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Component of (two-way) |
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Constraints
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Clarifications
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1The three <DRM Location> components of
a <DRM Image Anchor> instance
are interpreted as the locations of corners of the given
<DRM Image> instance, not those of
the centre of the texels in the corners
of the <DRM Image> instance.
When a <DRM Image Anchor> instance is interpreted
as a component of a <DRM Image> instance or as a
component of
a <DRM Image Mapping Function> instance
specifying a planar projection, the <DRM Location>
components of the <DRM Image Anchor> instance are
interpreted as follows.
The first <DRM Location> component specifies the
location to which the lower left corner of the
<DRM Image> instance is mapped.
The second <DRM Location> component specifies
the location to which the upper left corner of the
<DRM Image> instance is mapped.
The third <DRM Location> component specifies
the location to which the upper right corner of the
<DRM Image> instance is mapped.
When a <DRM Image Anchor> instance is interpreted
as a component of
a <DRM Image Mapping Function> instance
that specifies a non-planar projection, the
<DRM Location> components of the
<DRM Image Anchor> instance are interpreted
as follows.
For a cylindrical projection, the first
<DRM Location> component specifies
the centre of the cylinder. The second specifies a point
at the centre of the top of the cylinder, thus indicating
direction. The third <DRM Location> component
specifies the alignment
of the cylinder by specifying a point on the surface of
the cylinder.
For a spherical projection, the first
<DRM Location> component specifies
the centre of the sphere. The second specifies the point at
the north pole of the sphere, thus indicating
direction. The third <DRM Location> component
specifies a point on the equator of the sphere.
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Example(s)
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