Table 6.137—DRM_Image_Anchor
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Property |
Description |
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Superclass |
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Class |
· <DRM Image Anchor> |
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Subclass |
· none |
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Definition |
This class defines where (in the currently scoped 'world' spatial reference frame) a <DRM Image> is located. The three <DRM Location>s specified are the locations of corners of the <DRM Image>, NOT those of the centre of the texels in the corners of the <DRM Image>. <DRM Image Anchor> is used in two ways by the SEDRIS data representation model: a. <DRM Image Anchor> may be used as a component of a <DRM Image> in an <DRM Image Library>. In this case, the <DRM Image> is not tied to a particular textured object and the <DRM Location> components of the <DRM Image Anchor> merely define the (currently scoped ‘world’) locations of the corners of the <DRM Image>. Note that if two geo-referenced <DRM Image>s are to be placed exactly next to each other, the <DRM Location>s specified would be exactly the same along the common edge. b. A <DRM Image Anchor> may be used as a component of an <DRM Image Mapping Function>. In this case, the <DRM Image Anchor> defines how the associated <DRM Image> is to be applied to the <DRM Geometry> that has the <DRM Image Mapping Function> as a component. <DRM Image Anchor>s are used to support spherical and cylindrical image projections for <DRM Image Mapping Function>s. By specifying anchor points that are not in the same plane, non-orthogonal projection becomes possible. Note: When an image mapping is applied to many <DRM Polygon>s using a single <DRM Image Mapping Function>, a "continuous" image should be the result when displayed. |
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Example(s) |
· A producer has a geo-specific "global" texture that has been derived from overhead photography and rectified. It might, for example, be used to "drape" over a terrain surface. This would typically be represented as an Image (in a <DRM Image Library>) with a <DRM Image Anchor> component. · If a producer has a geo-referenced <DRM Image> data that is to be explicitly applied to one or more terrain <DRM Polygon>s, the mapping of the image data to the <DRM Polygon>s would be defined by an <DRM Image Mapping Function> (component of the <DRM Polygon>) that has a <DRM Image Anchor> and an association to the appropriate <DRM Image>. |
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Inherited field elements |
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Field elements |
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Associated to (one-way) (inherited) |
· none |
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Associated to (one-way) |
· none |
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Associated by (one-way) (inherited) |
· none |
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Associated by (one-way) |
· none |
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Associated with (two-way) (inherited) |
· none |
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Associated with (two-way) |
· none |
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Composed of (two-way) (inherited) |
· none |
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Composed of (two-way) |
· exactly three {ordered} <DRM Location>s1 |
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Composed of (two-way metadata) (inherited) |
· none |
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Composed of (two-way metadata) |
· none |
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Component of (two-way) (inherited) |
· none |
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Component of (two-way) |
· zero or more <DRM Image>s · zero or more <DRM Image Mapping Function>s |
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Constraints |
· none |
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Notes |
1 First is lower left; second is upper left; third is upper right. |
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Class diagram |