Class

• <DRM Volume LOD Data>

Superclass

• <DRM Base LOD Data>

Subclass

• None.

Definition

An instance of this DRM class specifies a volume that governs the switching of objects by the associated branch of a volume-based <DRM LOD Related Geometry> or <DRM LOD Related Features> instance.

For a <DRM Volume LOD Data> instance associated with a given branch of a volume-based level of detail aggregation, outside = TRUE if that branch is switched on when the observer is outside the volume, and off when the observer is inside the volume. If outside = FALSE, this behaviour is reversed.

Class diagram

Figure 6.359 — DRM_Volume_LOD_Data

Constraints

• LOD related organizing principle
• Publishable Object

Example(s)

• Consider a geometric representation of a runway for an application for which increased detail is required as a viewer gets within 1000m of it, but for which a less detailed representation can be used outside that volume. This geometric representation can be organized as a <DRM LOD Related Geometry> instance, wherein the branch corresponding to the less detailed representation has a <DRM Volume LOD Data> link object with outside set to TRUE, specifying a parallelepiped volume that is aligned with the runway and extends 1000m from each edge. The more detailed representation’s <DRM Volume LOD Data> link object would use the same <DRM Parallelepiped Volume Extent> instance and the same volume centre, but would have outside set to FALSE.

• Consider another application, for which a geometric representation of a runway is required to provide increased detail as a viewer gets within 1000m of either end, but which, if overflown from the side, does not require detail to be switched on until the viewer is 500m away. In this case, the representation would have the same structure as that used in the previous example, but the parallelepiped would extend only 500m from either side of the runway, while extending 1000m from each end.

• Consider a representation of a windowless building having opaque walls, such that nothing inside the building can be seen by an observer outside the building representation. Consequently, everything inside that building’s representation can be switched on and off depending on whether an observer is inside or outside the building. This can be represented by organizing the building interior’s representation with a volume level of detail organization.

  Suppose that the building interior’s feature representation is being considered, so that it is being represented as one branch of a <DRM LOD Related Features> instance in a geodetic SRF, and that the interior volume of the building can be represented as a parallelepiped as shown in Figure 6.360.

  

  Figure 6.360 — <DRM Volume LOD Data> example

  The <DRM Volume LOD Data> instance specifies a parallelepiped volume of the same dimensions as the building interior, and specifies the centre of that volume. The value of its outside field indicates that the building interior’s feature representation (the data represented by this branch) is active only when the viewer is inside the parallelepiped volume.