Class Name: Distance LOD Data

Superclass - <Base LOD Data>

Subclasses

Definition

An instance of this DRM class specifies a level of detail described in terms of distance from the eyepoint to the centre of the object.

For each <Distance LOD Data> instance, when moving the eyepoint away from the centre of the object, the representation begins to appear at minimum_range. The representation gradually gets stronger until it is fully visible at minimum_range + minimum_fade_band. As the eyepoint continues to move away from the centre of the object, the representation gradually starts to fade out at maximum_range - maximum_fade_band until it completely disappears at maximum_range. If fade bands are specified, adjacent levels shall overlap within those fade bands and not overlap any other portion of the adjacent level(s).

Primary Page in DRM Diagram:

• 9

Secondary Pages in DRM Diagram:

Example

1. Consider a <LOD Related Geometry> instance that has two branches, each through a <Distance LOD Data> link object as depicted in Figure 6.11:

   

   Figure 11 — <DRM Distance LOD Data> example

   The first <Distance LOD Data> link object has:

   minimum_range	100.0
   minimum_fade_band	10.0
   maximum_range	200.0
   maximum_fade_band	20.0

   The second <Distance LOD Data> link object has:

   minimum_range	200.0
   minimum_fade_band	10.0
   maximum_range	1000.0
   maximum_fade_band	10.0

   If the eyepoint is moving outward and the distance reaches 90, the first branch starts fading in. At a distance of 100, the first branch has totally faded in. At a distance of 180 the first branch starts to fade out. At a distance of 190 the second branch starts fading in. The first and second branches are both seen (superimposed) between the ranges of 190 and 200. At a distance of 200 the first branch is totally faded out, while the second branch is the only branch seen. At a distance of 990, the second branch starts fading out, and at 1000 it is completely faded out.

2. Consider a <LOD Related Geometry> instance which has two branches, each through a <Distance LOD Data> link object.

   The first <Distance LOD Data> link object has:

   minimum_range	50.0
   minimum_fade_band	20.0
   maximum_range	100.0
   maximum_fade_band	30.0

   The second <Distance LOD Data> link object has:

   minimum_range	110.0
   minimum_fade_band	15.0
   maximum_range	500.0
   maximum_fade_band	10.0

   If the eyepoint is moving outward and the distance reaches 30, the first branch starts fading in. At a distance of 50, the first branch has totally faded in. At a distance of 70 the first branch starts to fade out. At a distance of 95 the second branch starts fading in. The first and second branches are both seen (superimposed) between the ranges of 95 and 100. At a distance of 100, the first branch is totally faded out, while the second branch is the only branch seen, but has not completely faded in. At a distance of 110 the second branch has completely faded in. At a distance of 490 the second branch starts fading out, and at 500 is completely faded out.

3. A set of polygonal data is produced with low detail for viewing at ranges greater than 3200 metres, and organized as a <Union Of Primitive Geometry> instance, with a <Distance LOD Data> component specifying this viewing range so that the intended viewing distance at which these <Polygon> instances are to be used is provided.

4. See examples for <LOD Related Geometry>.

FAQs

Consider a data provider with a branch of a distance level-of-detail-related organization for which fade bands are not applicable. How should those fields be set?

If a target does not contain fade bands, the minimum_fade_band and maximum_fade_band shall be set to zero (0).

Constraints

• <<Publishable Object>>
• <<LOD Related Organizing Principle>>

Composed of (two-way)

• zero or one <Location> instance¹

Component of (two-way) (inherited)

• zero or more <Aggregate Feature> instances
• zero or more <Aggregate Geometry> instances
• zero or more <Property Grid Hook Point> instances

Inherited Field Elements

Field Elements

Notes

Composed of Notes

Location

Fields Notes

minimum_range

The minimum_range field is specified in metres as the minimum distance from the centre of the object.

minimum_fade_band

The minimum_fade_band field is expressed in metres relative to the minimum_range value. This fade band is defined to be adjacent to the minimum_range and further from the centre of the object.

maximum_range

The maximum_range field is specified in metres as the maximum distance from the centre of the object. SE_POSITIVE_INFINITY is a legal range value.

maximum_fade_band

The maximum_fade_band field is expressed in metres relative to the maximum_range value. This fade band is defined to be adjacent to the maximum_range and closer to the centre of the object.