Class

• <DRM Model>

Superclass

• <DRM SEDRIS Abstract Base>

Subclass

• None.

Definition

An instance of this DRM class specifies a representation of some environmental entity as a feature representation, a geometric representation, or both. This representation is usually a generic representation that can be referenced many times in a transmittal to create many instances of representations of similar environmental entities.

The special case termed the null model is the case in which both the feature and the geometric representation of the <DRM Model> are empty; that is, they contain no primitives. A null model is instanced in cases where some state or condition of a representation exists but has no primitives, such as a representation of an environmental entity that has been completely destroyed or that is out of viewing range.

The name field specifies a meaningful short name.

The srf_info field specifies the SRF within which the given <DRM Model> instance is defined.

The model_reference_type field specifies how the given <DRM Model> instance may be referenced within a transmittal.

The value of the dynamic_model_processing field is TRUE only if the given <DRM Model> instance is used by the data provider to represent something that moves throughout the environment, such as a vehicle. This flag is used to identify information at the top level of model data, so that it can be set at the level where model_reference_type is not COMPONENT.

The has_units field only takes effect if the srf_info are LSR; has_units allows a data provider to say “This LSR Model is in metres” vs. “This LSR Model is unitless (it has no units)”. In the former case, when an LSR model is specified in metres, it can be used to represent real-world things, such as a tank, a ship, or a tree. Sometimes, such a <DRM Model> is scaled when it is instanced. (<DRM Model>s representing trees are often scaled, but those representing ships and tanks aren’t.) In the latter case, when an LSR model has no units, the <DRM Model> cannot be instanced into another SRF.

The value of the has_moving_parts field is TRUE only if the given <DRM Model> contains at least one <DRM Control Link> attached to an <DRM LSR Transformation Step> instance that allows motion.

Class diagram

Figure 6.185 — DRM_Model

Constraints

• Hierarchy summary constraints
• Model reference type constraints
• Model spatial reference frame
• No attribute conflicts
• Non empty Model
• Publishable Object

Example(s)

• The lowest level of detail of a tank’s turret.

• A 1 degree by 1 degree tile of terrain containing thousands of instances to other <DRM Model> instances.

• An aircraft carrier that has both a geometric representation and a feature representation.

• A data provider has an overall model (e.g., an automobile) made up of several components: top, two sides, four tires, back, front, underneath. When put into this data provider’s <DRM Model Library>, each of these components (as well as the overall automobile placeholder) is represented as an instance of <DRM Model>. The data provider’s organization has a place in its database where “automobile” is instanced, so that at a visualization of that database the “automobile” appears. This is represented in the resulting transmittal by a <DRM Geometry Model Instance> of “automobile” appearing in the scope of an <DRM Environment Root>. No other <DRM Models> in this data provider’s mapping to a transmittal can reference the “automobile” <DRM Model>.

  In this case, the “automobile” will have model_reference_type set to ROOT, since “automobile” can be instanced outside the scope of the <DRM Model Library>, and in fact has a <DRM Geometry Model Instance> under an <DRM Environment Root>.

  On the other hand, the “top” <DRM Model>, representing the top of the car, cannot be instanced outside the <DRM Model Library> in the data provider’s scheme of things, but only as part of more complex <DRM Models>; consequently, the “top” <DRM Model> has model_reference_type COMPONENT.

• A producer has a <DRM Model> “plane” that has several components (two wings, tail, fuselage, etc). However, the producer has a <DRM Model> “ship” that instances “plane” to identify a ship with planes on its deck. The transmittal will instance “ship”, which has model_reference_type = ROOT. Since the <DRM Model> “plane” could be used elsewhere in the transmittal, its instance under “ship” has model_reference_type = ROOT_AND_COMPONENT.