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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> is located in the specified
SRF.
<DRM Image Anchor> is used in two ways:
- As a component of an <DRM Image> in an
<DRM Image Library>.
In this case, the <DRM Image> is not tied to a
particular <DRM Feature Representation> or
<DRM Geometry Representation>, and the
<DRM Image Anchor>’s
<DRM Location> components
merely specify the positions of the corners of the
<DRM Image> in the specified SRF.
Please note that if two geo-referenced <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 would be exactly the same along the common edge.
- As a component of an
<DRM Image Mapping Function>
instance.
In this case, the <DRM Image Anchor>
defines how the associated <DRM Image> is to be
applied to the object having the
<DRM Image Mapping Function>
instance as a component, and the SRF parameters
of the <DRM Image Anchor> shall match those
of the context in which the
<DRM Image Mapping Function>
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 that when an image mapping is applied to many
<DRM Polygon> instances using a single
<DRM Image Mapping Function>, a
continuous image should result when displayed.
The srf_info field
specifies the SRF within which the given
<DRM Image Anchor> instance is defined.
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Clarifications
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1
The three <DRM Location> components of an
<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>.
When an <DRM Image Anchor> is interpreted
as a component of an <DRM Image>, or as a
component of an
<DRM Image Mapping Function>
specifying a planar projection, the <DRM Location>
components of the <DRM Image Anchor> are
interpreted as follows.
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The first <DRM Location> component specifies the
location to which the lower left corner of the
<DRM Image> is mapped.
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The second <DRM Location> component specifies
the location to which the upper left corner of the
<DRM Image> is mapped.
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The third <DRM Location> component specifies
the location to which the upper right corner of the
<DRM Image> is mapped.
When an <DRM Image Anchor> is interpreted
as a component of an
<DRM Image Mapping Function> that
specifies a non-planar projection, the
<DRM Location> components of the
<DRM Image Anchor> are interpreted
as follows.
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For a cylindrical projection, the first
<DRM Location> 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>
specifies the alignment
of the cylinder by specifying a point on the surface of
the cylinder.
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For a spherical projection, the first
<DRM Location> 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>
specifies a point on the “equator” of the sphere.
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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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Field name
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Range
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Field data type
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srf_info
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SRF_Info
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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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Example(s)
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