The SEDRIS Data Representation Model
APPENDIX A - Classes
Conformal Behaviour

Class Name: Conformal Behaviour

Superclass - <SEDRIS Abstract Base>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

The <Geometry Hierarchy> to which a <Conformal Behaviour> is attached conforms to the terrain skin automatically, either "parallel to gravity" (e.g., ensuring that the base of a building touches the ground without warping the walls) or orthogonally to the terrain skin (e.g. a fence).

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

  1. A <Model> instanced to terrain. A <Geometry Model Instance> may specify that the location component of its <Transformation> is <Conformal Behaviour> to the terrain skin. The terrain skin may use a <Classification Related Geometry> aggregation to separate the surface that <Model> conforms to from the rest of the <Geometry>. If so, the <Conformal Behaviour> instance can associate with the terrain skin. This would help the consumer resolve ambiguities when deriving the actual 3D location. The surface to be conformed to can be further qualified by the <Property Value> that has been extended.

  2. Consider a tree canopy that conforms to multiple, or continuous LOD terrain. The entire collection of tree canopy <Polygon> instances and the tree wall <Polygon> instances around the canopy is aggregated into a <Classification Related Geometry>, which is associated with an <Areal Feature>.

    Each <Vertex> of the <Polygon> instances representing the tree wall around the canopy uses <Conformal Behaviour>. The <Conformal Behaviour> of each <Vertex> on the ground has parallel_gravity = SE_FALSE and offset_distance = 0, while the <Conformal Behaviour> of the <Vertex> instances at the top has parallel_gravity = = SE_TRUE and a positive offset_distance indicating the height of the tree wall. Each <Vertex> of the <Polygon> instances representing the tree canopy has a <Conformal Behaviour> with parallel_gravity = SE_TRUE and offset_distance indicating the height of the tree canopy.

  3. An airplane <Model> might have <Geometry> that represents the projected shadow. The <Geometry Hierarchy> containing the shadow could be given <Conformal Behaviour> so that it will hug the nominal terrain surface.

FAQs

Why has <Conformal Behaviour> been made into a class of its own and not implemented as a kind of <Control Link>?

<Conformal Behaviour> could be achieved via a <Translation Control Link> with a <Variable> that represents a Zenith (HAT) test. We have chosen to represent this kind of behaviour as a class of its own because it is a well-understood (abstracted) self-contained behaviour. This is also the case with <Stamp Behaviour> and level of detail. SEDRIS has generally been designed to allow for high-level abstraction as well as lower-level descriptions to exist in the same <Model>.

Constraints

None.

Component of (two-way)

Inherited Field Elements

This class has no inherited field elements.

Field Elements

SE_Boolean parallel_gravity; (notes)
SE_Float offset_distance; (notes)

Notes

Fields Notes


parallel_gravity

 If this value is SE_TRUE, the direction of conformance is parallel
 to gravity; otherwise, the direction of conformance is orthogonal
 to the terrain skin.

offset_distance

 This is the distance above the given surface, in metres.
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Last updated: May 15, 2003 Copyright © 2003 SEDRIS™