Class

• <DRM State Related Geometry>

Superclass

• <DRM Aggregate Geometry>

Subclass

• None.

Definition

An instance of this DRM class specifies a mechanism for specifying discrete states from a possibly continuous state value. Each discrete state corresponds to a branch of the <DRM State Related Geometry> instance and is identified by the <DRM State Data> instance for that branch; the state value itself is given by the state_tag of <DRM State Related Geometry> instance.

The state_tag field specifies the state by which the component <DRM Geometry Hierarchy> instances are being differentiated, and shall be an EAC that is designated as state applicable.

The active_state_value specifies the default state. If the given <DRM State Related Geometry> instance has a <DRM State Control Link> component, this field is the target of that <DRM State Control Link> instance.

Class diagram

Figure 6.313 — DRM_State_Related_Geometry

Constraints

• Colour Mapping restrictions
• Distinct geometric centre
• Distinct link objects
• Image Mapping Functions and Texture Coordinates
• No attribute conflicts
• Non crossing aggregations
• Non crossing associations
• Non cyclic aggregations
• Precedence of Property Set Index
• Publishable Object
• State related organizing principle

Example(s)

• Consider a <DRM Model> instance of a building that has four different geometric representations, each representing different damage states. The <DRM Model> instance therefore has a <DRM Geometry Model> instance, the geometry of which is organized via a <DRM State Related Geometry> instance with four branches, one for each damage state, as shown in Figure 6.314.

  

  Figure 6.314 — <DRM State Related Geometry> four representation example

  Each branch of the <DRM State Related Geometry> has a <DRM State Data> indicating the range of percent damage that the branch represents. The range values in the diagram therefore specify explicitly the “bins” in which the states fall.

• A slightly different design for example 1, modified to allow each <DRM Geometry Model Instance> instance to specify a percent damage value via a <DRM State Control Link> instance.

  1. Add a <DRM State Control Link> component to the <DRM State Related Geometry> instance, with mismatch_behaviour = NONE and a <DRM Variable> instance V as its controlling <DRM Expression> instance, where V’s meaning is EAC_GENERAL_DAMAGE_FRACTION.

  2. Associate V to the <DRM Interface Template> component of the <DRM Model> instance. If the <DRM Model> instance has no <DRM Interface Template> instance, create one.

  The mismatch_behaviour of the <DRM State Control Link> instance can be exploited to turn off the <DRM Geometry Model Instance> instance if a damage value is provided which does not match one of the damage states. This is allows the <DRM Model> instance to not require a totally destroyed state for 100% damage.

  If the data provider instead wanted to keep a state transition from happening until the state value matches a <DRM State Data> instance, LAST would be specified.

  The mismatch_behaviour would not be needed if the <DRM Variable> instance only took on valid values (0,0, 0,5, 0,75, or 1,0), but this scheme does not force state values to be discrete.

• A wind sock model designed to support a landing site has state behaviour to allow it to respond to wind speed and wind direction. The wind sock is modeled with five states of EAC_WIND_RESPONSE, where the response to wind direction is implemented by using a <DRM Rotation Control Link> instance tied to an EAC_WIND_DIRECTION <DRM Variable> instance.

  

  Figure 6.315 — <DRM State Related Geometry> wind example

• Identifies one of alternative appearances for some state-applicable attribute.

  1. For a <DRM State Related Geometry> instance representing different states of an aircraft hatch for EAC_OPENING_COVER_POSITION, one <DRM State Data> instance with EEC_OPNCOVPOS_CLOSED and another with EEC_OPNCOVPOS_OPEN.

  2. For a <DRM State Related Geometry> instance representing different damage states of a building for EAC_GENERAL_DAMAGE, <DRM State Data> instance for [0, 25) % damage, [25, 50)% damage, [50, 75)% damage, and [75, 100]% damage.

  3. For a <DRM State Related Geometry> instance representing different states of a forest for healthy versus burned, EAC_GENERAL_DAMAGE could be used.