Class Name: GCS Location 3D

Superclass - Location 3D

Definition

A coordinate within the Global Coordinate System (GCS) 3D Spatial Reference Frame (SRF).

The GCS Spatial Reference Frame defines multiple local Cartesian coordinate systems with origins at individual discrete locations on the Object Reference Model/Earth Reference Model (ORM/ERM) defined by the WGS-84 reference ellipsoid. Each local Cartesian coordinate system is referred to as a "cell"; the ORM/ERM surface is completely tiled by GCS cells. For much of the ORM/ERM surface, each cell covers 1 degree of geodetic latitude by 1 degree of geodetic longitude. However, near the poles, many degrees of longitude are grouped together into a single GCS SRF cell since an arc degree of longitude becomes arbitrarily small near the poles. GCS SRF cells are always 1 degree of latitude high.

Within each GCS SRF cell, a local Cartesian frame of reference is defined. The origin of each Cartesian coordinate system is the point of tangency of the reference surface with the ORM/ERM WGS-84 ellipsoid. A 2D local origin offset is provided. The point of tangency is at the center of the rectangular GCS SRF cell, even if more than one degree of geodetic longitude falls within a GCS SRF cell. The X axis is aligned with the local parallel and is positive towards the east. The Y axis is aligned with the local meridian and is positive towards the north. The Z axis is an outward normal vector from the reference ellipsoid at the point of tangency forming a 3D right-handed coordinate system.

The GCS SRF is effectively a large collection of LTP SRFs with well-defined parameters. The local Cartesian coordinate system for each GCS SRF cell extends arbitrarily far in all directions, although by convention, every georeferenced location has a "preferred" GCS SRF cell to which it is referenced (by cell ID).

See the SEDRIS Spatial Reference Model (SRM) for additional details.

Primary Page in DRM Diagram:

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Example

FAQs

Is the GCS SRF projection-based?

No. The GCS SRF is a collection of Local Tangent Plane (LTP) SRFs. Within each, the Z value of the surface of the ORM/ERM is negative excepting at the origin (point of tangency).

Constraints

• Environment Root Spatial Reference Frame
• Locations Under Model

Component of (one-way)(inherited)

• optionally, some Arcs
• optionally, some Base Perimeter Data
• optionally, some Base Reference Vectors
• optionally, some Directional Light Behaviors
• optionally, a Distance Level of Detail Data (notes)
• optionally, some Ellipses
• optionally, some Elliptic Cylinders
• optionally, some Feature Edges
• optionally, a Feature Node
• optionally, some Image Anchors
• optionally, some Labels
• optionally, a Location Table
• optionally, some Morph Points
• optionally, some Point Geometries
• optionally, some Property Grid Hook Points
• optionally, a Reference Origin
• optionally, some Spatial Domains
• optionally, some Spatial Index Related Feature Topologies
• optionally, some Spatial Index Related Features
• optionally, some Spatial Index Related Geometries
• optionally, some Tack Points
• optionally, some Vertices
• optionally, some Vertex with Component Indices
• optionally, some World 3X3s
• optionally, some World Transformations
• optionally, an Attachment Point
• optionally, some Center of Buoyancies
• optionally, some Center of Mass
• optionally, some Center of Pressures
• optionally, a Contact Point
• optionally, some Positional Lights
• optionally, some Separating Planes
• optionally, some Sound Instances
• optionally, some Stamp Behaviors
• optionally, some Volumes
• optionally, some Volume Level of Detail Data
• optionally, some Volume Light Behaviors

Field Elements

Notes

Component of Notes

Distance_Level_of_Detail_Data

 the center point for the LOD test

Fields Notes

cell_ID

 between 1 and 49778, inclusive

x

 in meters, positive Eastward

y

 in meters, positive Northward

z

 in meters, the height or elevation value; positive along xy
 surface normal