The SEDRIS Data Representation Model
APPENDIX A - Classes
Image Library

Class Name: Image Library

Superclass - <Library>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class specifies the complete list of unique <Image> instances resident within the transmittal.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

  1. A <Image> instance in the <Image Library> instance can represent imagery intended to be texture-mapped to DRM objects in the transmittal.

    Consider an <Image Library> instance with an <Image> component that depicts a tree and a <Model> instance representing a tree, where the geometry of the <Model> instance consists of a single <Union Of Primitive Geometry> instance containing a single <Polygon> component P and having a <Stamp Behaviour> component as depicted in Figure 6.24.

    Here, the <Stamp Behaviour> instance allows P to be rotated at run-time so that the texture-mapped side always faces the observer.

    Image Library, Example 1

    Figure 24 — <DRM Image Library> example

    Each <Vertex> component of P has a <Texture Coordinate> component that is used, together with the <Image Mapping Function> instance, to place the imagery on P.

  2. A <Image> instance in the <Image Library> instance can represent imagery applied to a large number of polygons at once, where the <Polygon> instances are grouped under some <Aggregate Geometry> instance with an <Image Mapping Function> component.

    In this case, the <Image Mapping Function> instance determines the placement of the imagery within the currently scoped SRF. The imagery is then applied to the <Polygon> instances after they have been located within the specified SRF.

    This method has two common uses:

    1. the application of a geospecific image to many polygons in a seamless image, or

    2. the application of a single image to a large number of polygons within a <Model> instance (e.g., the image of an aircraft is wall-papered onto all the polygons within the <Model> instance representing that aircraft).

  3. A <Image> instance in the <Image Library> instance can represent imagery to be transmitted that is not used by any <Image Mapping Function> instance. This imagery normally has anchor points, represented by an <Image Anchor> component of the <Image> instance.

FAQs

Can a transmittal contain <Image> instances that are not components of an <Image Library> instance?

No.

Is an <Image Library> instance permitted to have <Image> components that are not referenced through <Image Mapping Function> instances elsewhere in the transmittal?

Yes.

Constraints

Composed of (two-way)

Composed of (two-way metadata) (inherited)

Component of (two-way)

Inherited Field Elements

This class has no inherited field elements.
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Last updated: July 26, 2006 Copyright © 2006 SEDRIS