The SEDRIS Data Representation Model
APPENDIX A - Classes
Distance Level Of Detail Data

Class Name: Distance Level Of Detail Data

Superclass - <Base Level Of Detail Data>

Subclasses

This DRM class is concrete and has no 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.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

This class appears on only one page of the DRM class diagram.

Example

  1. Consider a < Level Of Detail Related Geometry> instance which has two branches, each having an attached <Distance Level Of Detail Data>.

    The first < Distance Level Of Detail Data> instance has: 

            minimum_range = 100
        minimum_fade_band = 10
        maximum_range = 200
        maximum_fade_band = 20
    The second < Distance Level Of Detail Data> instance has: 
            minimum_range = 200
        minimum_fade_band = 10
        maximum_range = 1000
        maximum_fade_band = 10
    If we are 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 (super-imposed) 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 < Level of Detail Related Geometry> instance which has two branches, each having an attached <Distance Level Of Detail Data>.

    The first < Distance Level Of Detail Data> instance has: 

           minimum_range = 50
       minimum_fade_band = 20
       maximum_range = 100
       maximum_fade_band = 30

    The second < Distance Level Of Detail Data> instance has: 

           minimum_range = 110
       minimum_fade_band = 15
       maximum_range = 500
       maximum_fade_band = 10
    If we are 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 (super-imposed) 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 hasn't 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>, with a < Distance Level Of Detail Data> component specifying this viewing range so that the intended viewing distance at which these <Polygons> are to be used is provided.

  4. See < Level Of Detail Related Geometry>'s examples.

FAQs

As a data provider, I have a branch of a distance level-of-detail-related organization for which fade bands aren't applicable. How should those fields be set?

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

Constraints

Composed of (two-way)

Component of (two-way)(inherited)

Inherited Field Elements

This class has no inherited field elements.

Field Elements

SE_Long_Float minimum_range; (notes)
SE_Long_Float minimum_fade_band; (notes)
SE_Long_Float maximum_range; (notes)
SE_Long_Float maximum_fade_band; (notes)

Notes

Composed of Notes


Location

 This is the centre point for the LOD test.

Fields Notes


minimum_range

 This is in metres.

minimum_fade_band

 This is expressed in metres (not percent). This fade band shall
 go in the negative direction from the minimum range.

maximum_range

 This is in metres; SE_POSITIVE_INFINITY is a legal range value.

maximum_fade_band

 This is expressed in metres (not percent). This fade band shall
 go in the negative direction from the maximum range.
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Last updated: October 1, 2002 Copyright © 2002 SEDRIS™