Temporal Components


Contents

Related pages


Schema documents

  • XmmlCVS:gml/base/temporal.xsd
  • XmmlCVS:gml/base/temporalTopology.xsd
  • XmmlCVS:gml/base/temporalReferenceSystems.xsd
  • XmmlCVS:gml/base/dynamicFeature.xsd
  • XmmlCVS:XMML/temporal.xsd


GML Temporal Components

The GML schemas include a comprehensive set of components for temporal information, and some basic components for dynamic features. GML temporal is fully documented in the GML specification from Open GIS Consortium, currently undergoing standardisation through ISO TC 211, and expected to appear in 2004 or 2005 as ISO 19136. The GML schema provides an XML implementation of most of the model described in ISO 19108 Geographic Information: Temporal Schema.

The following concrete components are defined in GML. For details, see documentation in the GML 3.1 specification:

Temporal Geometry

  • gml:TimeInstant
  • gml:TimePeriod
  • gml:duration, gml:timeInterval
  • gml:timePosition
  • gml:validTime

Temporal Topology

  • gml:TimeTopologyComplex
  • gml:TimeNode
  • gml:TimeEdge

GML temporal geometry and topology components are summarized in the following UML class diagram:

  • GML Temporal primitives and complexes:
    gmlTemporal.png

Temporal Reference Systems

  • gml:TimeCoordinateSystem
  • gml:TimeOrdinalReferenceSystem, gml:TimeOrdinalEra
  • gml:TimeCalendar, gml:TimeCalendarEra; gml:TimeClock

GML temporal reference systems are summarized in the following UML class diagram:

  • GML Temporal reference systems:
    gmlTRStop.png

  • GML Temporal Ordinal Reference System:
    gmlTORS.png

Dynamic Features

  • gml:history
  • gml:track
  • gml:MovingObjectStatus

XMML Temporal Components

Additional components for dealing with temporal information have been added in XMML. These include the following:

Temporal Geometry Complex

Model from XmmlCVS:XMML/temporal.xsd

Model

TimeGeometricComplex.png

Explanation

The model for a Temporal Geometry Complex follows the pattern of Geometric Complexes such as gml:CompositeCurve and Temporal Topology Complex. A TimeGeometricComplex is composed of one or more primitive elements, which indicate Time Primitives (i.e. gml:TimeInstant or gml:TimePeriod).

The compact (simpleContent) representation of time position may be used directly through the primitivePos property element, as an alternative to xmml:primitive/gml:TimeInstant/gml:timePosition form, when it is not required to make the component instant an "object with identity" (see LabelsAndHandles).

Temporal Grids

Model from XmmlCVS:XMML/temporal.xsd

Model

TimeGrid.png
TimePeriodGrid.png

Explanation

A temporal geometry complex may be composed of a regularly spaced sequence of primitives. This is common in geophysics, where the value of a phenomenon is often sampled on a regular time basis. It is natural and efficient to describe these cases using an implicit notation, similar to the spatial grid model.

The values of the dimension (="1") and axisName (="time") properties are fixed so may be omitted. The following properties are required to define a TimeGrid registered to a natural time system:

  • the extent, either as
    • a SeriesEnvelope in grid coordinates - low and high integer values
    • a gml:TimePeriod
  • the position of grid coordinate "0", given either
    • as a direct time position using the originPos property
    • by an origin property that indicates a gml:TimeInstant
  • the spacing of the points, given either as
    • offsetDuration using the XML Schema "duration" notation
    • offsetInterval using a notation that represents the ISO/IEC 11404 time interval model

The TimePeriodGrid represents a regular sequence of periods starting at the instants specified. One additional property is required:

  • the (constant) length of the periods, given either as
    • windowDuration using the XML Schema "duration" notation
    • windowInterval using a notation that represents the ISO/IEC 11404 time interval model

Note that the alternative representations of time lengths, used for both offsets and windows, match the alternative forms gml:duration, gml:timeInterval provided in the temporal geometry schema.


Issues and change requests

Readers are invited to add issues to this table - select [Edit Table] below. It is not mandatory to enter a solution, but change requests are more likely to be implemented if a concrete solution is proposed.

%EDITTABLE{ header="| # | By | Timestamp | Component(s) | Description of issue | Proposed solution | Resolution |" format="| row, -1 | text, 25, Unknown | label, 0, 24 Mar 2017 12:20 | textarea, 3x25, Component(s) | textarea, 3x25, Description | textarea, 3x25, Proposal | select, 1, Unaddressed, Progressing, Resolved |" changerows="on" }%
# By Timestamp Component(s) Description of issue Proposed solution Resolution
1 My org 14 May 2004 component A A big whinge a proposed solution Unaddressed


Topic revision: r14 - 15 Oct 2010, UnknownUser
 

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