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GeoPose 1.0 Change Request

“Components”

Steve Smyth

6 December 2023

Updated 13 December 2024

Presented 18 June 2024 at OGC Member Meeting Montreal

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“Components” Request

Summary

Targeted standard: OGC GeoPose 1.0
Description:

Create requirements, conformance classes, and conformance tests for the GeoPose Structural Data Units (SDUs). Call them Components.

Motivation

This will allow interoperable use of the SDUs individually, or in groups. In particular, this will support redefining the eight GeoPose standardization targets in terms of the Components as well as the standalone use of Components in other standards and applications.

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“Components” Request

Background 1/5

Components supply a framework for incremental development of additional ways of specifying frame transforms and orientations.
For example, other standards (e.g. OGC Moving Features) have elements that correspond to one or more GeoPose SDUs. Sharing a Component specification enhances interoperability and code-sharing.
The Components needed to define a “modular GeoPose” already exist in the GeoPose 1.0 logical model and are embedded in the JSON encoding JSON Schema specifications: https://github.com/opengeospatial/GeoPose/blob/main/standard/standard/schemata/GeoPose.Basic.Quaternion.Schema.json

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Background 2/5

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Some existing and possible new Components:

Basic: No Change

Geodetic position (latitude, longitude, height above WGS84 ellipsoid)
Rotation angles (angles of rotation about three axes - Z0, XP, YPP default)
Rotation quaternion (unit quaternion giving rotation about X0, Y0, Z0)

New Use of Existing Construct

CRS or reference frame context: an ID that comes from somewhere EPSG/IAOGP
Proper timeCoordinate (Unix? time coordinate)

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Background 3/5

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Building GeoPose 1.0 from Components:

Composition

position+angles => Basic YPR
position+quaternion => Basic Quaternion

With Timestamps

position+angles+timeStamp => Timestamped Basic YPR*
position+quaternion+timeStamp => Timestamped Basic Quaternion*

Notes

The order of appearance of a Component has no significance
* = not in GeoPose 1.0
GeoPose 1.0 does not prohibit timeStamp
Main change is to make the blocks first class objects

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“Components” Request

Background 4/5

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Using Components in a Local Cartesian Frame:

Composition

offset+angles => Local YPR
offset+quaternion => Local Quaternion

With Timestamps

offset+angles+time => Timestamped Local YPR*
offset+quaternion+time => Timestamped Local Quaternion*

Notes

offset is very useful.
Same pattern as Basic but transform is a 3D translation.

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Background 5/5

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New Components to Support Alternate Naming of Axes and Rotations:

axes

Forward, Right, Up with corresponding +/-X, +/-Y, +/-Z
Example: “axes”: “+Y+Z-X” for glTF

rotations

Example: “rotations”: “ZoYpXpp”
Means: Rotate about original Z axis, then rotate about the Y axis in the rotated coordinate system,then rotate about the X axis in the twice rotated coordinate system.

Notes

Needs a simple grammar or other definition for the strings.

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Use Cases

Basic, Advanced, Composite GeoPose
Embeddings in other standards

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Requirements

Individual Component

requirements
conformance classes
conformance tests

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Backwards Compatibility

Backwards compatible if no new Components specified.

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Encoding

Same as GeoPose 1.0

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Examples

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Demos

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References

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