2.1.  Modularity

This standard describes eight standardization targets. These targets are independent and a conforming implementation may implement one or more of the targets.

2.2.  Conformance classes

This OGC® standard identifies eight conformance classes. One conformance class is defined for each corresponding set of Structural Data Units (SDUs) where each SDU is linked to the Logical Model as an alias for a class or attribute. Additionally, each of the eight standardization targets is represented by a conformance class as defined by a corresponding requirements class.

The tests in Annex A are organized by requirements class. An implementation of a conformance class must pass all tests specified in Annex A for the corresponding requirements class.

No conformance class has a dependency on another conformance class.

The Logical Model is the root normative part of this standard.

2.3.  Standardization targets

There are eight independent standardization targets. Each addresses the specific requirements of one or more individual use cases. The Basic and Advanced Targets share in the use of an EPSG 4979/3D WGS-84 outer frame (Clause 4.2.7) but differ in the level of options and flexibility in specification of the inner frame (Clause 4.2.8). The Composite Targets offer approaches to packaging sequenced or linked Frame Transforms.

The eight targets are denoted by bold terms in the following categories:

1. Basic — Satisfy most use cases — EPSG 4979 Outer Frame

   1. Local Tangent Plane East, North, Up (LTP-ENU) inner frame (Clause 4.2.8) oriented by Yaw, Pitch, and Roll (YPR) rotations about z, y, x axes: Basic-YPR Target

   2. LTP-ENU inner frame (Clause 4.2.8) oriented by unit quaternion: Basic-Quaternion Target

2. Configurable inner frame (Clause 4.2.8) oriented by unit quaternion — Flexible enough for complex use cases: Advanced Target

3. Composite — Efficient structures for linked and sequential GeoPoses

   1. Linked linear sequence of poses: Chain Target

   2. General linked poses: Graph Target

   3. Sequence

      1. Series

         1. Time series with constant time spacing: Regular Time series Target

         2. Time series with per-GeoPose time: Irregular Time series Target

      2. Open-ended sequence of time-stamped GeoPoses: Stream Target

4.1.  Basic concepts

4.1.1. conceptual model

CM ADMITTED

model that defines concepts of a universe of discourse

[SOURCE: ISO 19101-1:2014, Clause 4.1.5]

4.1.2. logical model

logical information model ADMITTED

LM ADMITTED

information model that specifies the structures and relationships between data elements but is independent of any particular technology or implementation environment

[SOURCE: ISO 13972:2022, Clause 3.1.8]

4.1.3. structural data unit

SDU ADMITTED

element of the logical model (Clause 4.1.2) expressed in concrete data objects encoded using specific encoding or serialization technologies

4.2.  Spatial concepts

4.2.1. position

OGC direct position ADMITTED

set of coordinates of a point in a 3D Euclidean space and associated reference frame (Clause 4.2.5)

4.2.2. orientation

rotational relationship between two reference frames (Clause 4.2.5)

4.2.3. pose

representation of a frame transform (Clause 4.2.6) mapping the space of an outer frame (Clause 4.2.7) to the space of an inner frame (Clause 4.2.8)

4.2.4. GeoPose

pose (Clause 4.2.3) whose associated outer frame (Clause 4.2.7) or a pose chain (Clause 4.2.17) whose associated outermost frame (Clause 4.2.9) is a topocentric frame (Clause 4.2.12) defined by an extrinsic frame specification (Clause 4.2.14) related to the ephemeris object (Clause 4.2.11) planet Earth.

4.2.5. reference frame

system of location and measurement often defined by a frame specification (Clause 4.2.13) usually including a coordinate system to be used within a corresponding space

4.2.6. frame transform

pair of reference frames (Clause 4.2.5) and a bi-continuous coordinate transformation relating points in the corresponding spaces

4.2.7. outer frame

outer reference frame ADMITTED

first of two reference frames (Clause 4.2.5) associated with a frame transform (Clause 4.2.6)

4.2.8. inner frame

inner reference frame ADMITTED

second of two reference frames (Clause 4.2.5) associated with a frame transform (Clause 4.2.6)

4.2.9. outermost frame

outer frame (Clause 4.2.7) of the first frame transform (Clause 4.2.6) in a pose chain (Clause 4.2.17)

4.2.10. innermost frame

inner frame (Clause 4.2.8) of the last frame transform (Clause 4.2.6) in a pose chain (Clause 4.2.17)

4.2.11. ephemeris object

physical object or manifestation of a physical object that can be characterized by an externally-defined (possibly time-dependent) location and orientation in a 3-dimensional space

4.2.12. topocentric frame

topocentric reference frame ADMITTED

frame (Clause 4.2.5) that has an extrinsic frame specification (Clause 4.2.14) associated with a location on or near the surface of a natural body, such as planet Earth

4.2.13. frame specification

data that completely and uniquely defines a reference frame (Clause 4.2.5)

4.2.14. extrinsic frame specification

extrinsic specification ADMITTED

relates a reference frame (Clause 4.2.5) to an ephemeris object (Clause 4.2.11) or other external reference, which may be based on joint properties of a group of objects

Example

4.2.15. derived frame specification

derived specification ADMITTED

relates a reference frame (Clause 4.2.5) to another reference frame (Clause 4.2.5) by a frame transform (Clause 4.2.6) or its inverse

4.2.16. frame graph

reference frame graph ADMITTED

directed acyclic graph representation of the transformational relationships between reference frames (Clause 4.2.5)

4.2.17. pose chain

directed path in a frame graph (Clause 4.2.16) connecting an outermost frame (Clause 4.2.9) to an innermost frame (Clause 4.2.10)

4.3.  Sequence and stream concepts

4.3.1. sequence

GeoPose sequence ADMITTED

set of poses (Clause 4.2.3) ordered by valid time (Clause 4.5.1) and pertaining to the same underlying physical object or construct

4.3.2. inter-pose duration

time duration (Clause 4.4.5) between consecutive poses (Clause 4.2.3) in a sequence (Clause 4.3.1)

4.3.3. closed sequence

closed pose sequence ADMITTED

sequence (Clause 4.3.1) of fixed length with specific meta-data that fully characterize the sequence and its member poses (Clause 4.2.3)

4.3.4. regular sequence

regular GeoPose sequence ADMITTED

closed sequence (Clause 4.3.3) with a constant inter-pose duration (Clause 4.3.2)

4.3.5. irregular sequence

irregular GeoPose sequence ADMITTED

closed sequence (Clause 4.3.3) with a variable inter-pose duration (Clause 4.3.2)

4.3.6. GeoPose stream

irregular sequence (Clause 4.3.5) of unbounded length

4.3.7. header

sequence header ADMITTED

metadata essential for interpretation of the following members of a sequence (Clause 4.3.1)

4.3.8. transition model

metadata that indicates whether or how it may be possible to estimate poses (Clause 4.2.3) in the interval between consecutive poses (Clause 4.2.3) in a sequence (Clause 4.3.1)

4.3.9. trailer

sequence trailer ADMITTED

metadata essential for validation of the preceding members of a sequence (Clause 4.3.1).

4.4.  Temporal concepts

4.4.1. temporal frame

specification for the interpretation of points on a time line (Clause 4.4.2) as instants (Clause 4.4.3) in relation to a specified epoch (Clause 4.4.6)

4.4.2. time line

time axis ADMITTED

one-dimensional Euclidean space whose points represent an ordered sequence of instants (Clause 4.4.3) directed from the past to the future

4.4.3. instant

specific point on a time line (Clause 4.4.2)

4.4.4. interval

timespan between two instants (Clause 4.4.3) on a time line (Clause 4.4.2), interpreted in context of the associated temporal frame (Clause 4.4.1)

4.4.5. duration

one-dimensional signed distance between the bounding instants (Clause 4.4.3) of an interval (Clause 4.4.4)

4.4.6. epoch

specified instant (Clause 4.4.3) that can be used as a reference point to calculate temporal relationships (Clause 4.4.7) and durations (Clause 4.4.5) between instants (Clause 4.4.3).

4.4.7. temporal relationship

relationship between two instants (Clause 4.4.3)

4.5.  Temporal database concepts

4.5.1. valid time

time line (Clause 4.4.2) where the time of changes in the existence or validity of real-world objects or property values are located.

4.5.2. transaction time

time line (Clause 4.4.2) where the time of changes in the presence or validity of the representations of real-world objects or their properties in an information system are located

4.5.3. bi-temporality

property of a data representation that denotes that it carries both valid time (Clause 4.5.1) and transaction time (Clause 4.5.2)

5.1.  Identifiers

The normative provisions in this document are denoted by the URI

http://www.opengis.net/spec/GeoPose/1.0

All requirements and conformance tests that appear in this document are denoted by partial URIs which are relative to this base.

5.2.  Use Cases, Concepts, Logical Model, Standardization Targets, Encodings

5.3.  UML Notation

The logical structure of the elements used in the GeoPose Standard is presented in this document in diagrams using the Unified Modeling Language (UML) static structure diagram (see Booch et al. [10]). The UML notations used in this standard are described in the diagram in Figure 1.

All associations between model elements in GeoPose are uni-directional. Thus, associations in GeoPose are navigable in only one direction. The direction of navigation is depicted by an arrowhead. In general, the context an element takes within the association is indicated by its role. The role is displayed near the target of the association. If the graphical representation is ambiguous though, the position of the role has to be drawn to the element the association points to.

In order to enhance the readability of the GeoPose UML diagrams, classes are depicted in different colors. The following coloring scheme is applied:

Classes painted in grey represent data types.

Classes painted in blue are internal less-derived elements that are not themselves directly encoded as concrete data objects.

Classes painted in yellow correspond to Structural Data Units or have properties that are represented in Structural Data Units and in encodings of those SDUs. Only data types and classes painted yellow are encoded as concrete data objects.

Enumerations are painted in green.

The color white is used for notes and OCL constraints that are provided in the UML diagrams.

6.1.  General

ISO 19101-1:2014 defines a universe of discourse to be a view of the real or hypothetical world that includes everything of interest. That standard defines a conceptual model to be a model that defines concepts of a universe of discourse.

The goal of this GeoPose Standard is to establish and document a common set of concepts that spans the targeted use cases. This does not attempt to redefine application concepts, but merely to present a common set of concepts from and to which their concepts can be understood and mapped.

The GeoPose Conceptual Model (CM) is a graph of related concepts. One technology-independent realization is given by the GeoPose Logical Model (LM).

The GeoPose CM consists of linked definitions of terms denoting concepts expressed in the GeoPose LM and Structural Data Unit (SDU) specifications for the standardization targets.

The CM describes a (non-normative) domain of discourse for terms used in defining a precise and normative LM expressed as a Unified Modelling Language (UML) class diagram.

The scope of the standardization targets is a subset of the scope of the LM. The scope of the LM is a subset of the scope of the CM. The standardization targets are mutually independent implementations of subsets of the LM.

6.2.  Temporal concepts and reference frame

The only temporal frame used in this GeoPose standard is “Unix Time”: seconds since the Unix Epoch of 1 January 1970 measured by a virtual “Unix clock”, ticking once per “Unix second”, and omitting any corrections such as leap seconds.

Times before 1 January 1972 are not precisely related to another temporal frame but the value at UTC 1 January 1972 was +63,072,000. This allows precise conversion to and from modern temporal frames.

Temporal concepts defined in this document are intended to align with terms used in W3C CR-owl-time-20200326.

6.3.  Document structure

The structure of the GeoPose Standard document flows from:

• use cases to the definition of a conceptual domain of discourse comprehensive enough to support those use cases,

• a realization of a portion of that conceptual domain with an implementation-neutral but specific and normative logical data model expressed in UML, and

• the normative derivation of specific structural data units that represent abstract implementation and standardization targets.

These Structural Data Units (SDUs) are abstract: they are independent of implementation or delivery technology and serialization or encoding formats. GeoPose 1.0 specifies one of many possible realizations of the structural data units in JSON.

A key aspect of the GeoPose Standard is that specific use cases are tied to the standardization targets, which prescribe the structure and content of GeoPose data objects. Corresponding implementation examples appear in other documents.

Of course, GeoPose must incorporate or align with other relevant existing standards and common practices. The goal is to fill an interoperability gap in existing standards without reinventing technology in a way that encourages interoperability.

6.4.  Use Case Summary

The GeoPose use cases involve interactions between information systems or between an information system and a storage medium. The essential role of a GeoPose is to convey the position and orientation of a real or virtual object. The possibility of chained transformational relationships and cross-linkages between chains affords representation of complex pose relationships and a way to bring a collection of related GeoPoses in a common geographic reference frame.

Each use case is identified by a unique ID, has a brief description, and a list of the relevant standardization targets.

7.1.  General

The Frame Transform is the core abstraction in the GeoPose Standard. The Frame Transform is a representation of the transformation taking an Outer Frame coordinate system to an Inner Frame coordinate system. This abstraction is constrained in GeoPose v1.0 to only allow transformations involving translation and rotation. The intention is to match the usual concept of a pose as a position and orientation. The formalism that expresses a GeoPose Frame Transform is a pair of Reference Frames, Outer and Inner, each defined by a Frame Specification. The Logical Model relates these elements to represent different types of GeoPose data objects and also defines structures built of time series and linked GeoPoses.

7.2.  UML Logical Model

The normative expression of the UML model is a Sparx Systems Enterprise Explorer project (“eapx”) file located at:

• https://uml.opengis.net/geopose/1.0/geopose-1_0-model.eapx

The Logical Model consists of four top-level packages: Core, Time, Sequence, and Targets. The Targets package contains two detail packages: Basic and Composite. The Composite package is in turn subdivided into a Linked package and a Sequence package. The Basic GeoPose targets depend on only the Core package. The Advanced GeoPose target also depends on the Time Package. Composite GeoPoses depend on all four top-level packages.

The coloring of the classes indicates their role in the logical design. Note that the classes and data types defined in the Target packages are the source of structural data units (SDUs) that may be realized as concrete data objects.