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" (for example, ensuring that the base of a building touches the ground without warping the walls) or orthogonally to the terrain skin (for example, as in the case of 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 Representation>. 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 Representation> 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> instance with a <Variable> component 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

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

offset_distance

 The offset_distance field specifies the distance above the
 given surface, in metres.
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Last updated: July 16, 2004 Copyright © 2004 SEDRIS™