License Agreement

Permission is hereby granted by the Open Geospatial Consortium, ("Licensor"), free of charge and subject to the terms set forth below, to any person obtaining a copy of this Intellectual Property and any associated documentation, to deal in the Intellectual Property without restriction (except as set forth below), including without limitation the rights to implement, use, copy, modify, merge, publish, distribute, and/or sublicense copies of the Intellectual Property, and to permit persons to whom the Intellectual Property is furnished to do so, provided that all copyright notices on the intellectual property are retained intact and that each person to whom the Intellectual Property is furnished agrees to the terms of this Agreement.

If you modify the Intellectual Property, all copies of the modified Intellectual Property must include, in addition to the above copyright notice, a notice that the Intellectual Property includes modifications that have not been approved or adopted by LICENSOR.

THIS LICENSE IS A COPYRIGHT LICENSE ONLY, AND DOES NOT CONVEY ANY RIGHTS UNDER ANY PATENTS THAT MAY BE IN FORCE ANYWHERE IN THE WORLD.

THE INTELLECTUAL PROPERTY IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE DO NOT WARRANT THAT THE FUNCTIONS CONTAINED IN THE INTELLECTUAL PROPERTY WILL MEET YOUR REQUIREMENTS OR THAT THE OPERATION OF THE INTELLECTUAL PROPERTY WILL BE UNINTERRUPTED OR ERROR FREE. ANY USE OF THE INTELLECTUAL PROPERTY SHALL BE MADE ENTIRELY AT THE USER’S OWN RISK. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR ANY CONTRIBUTOR OF INTELLECTUAL PROPERTY RIGHTS TO THE INTELLECTUAL PROPERTY BE LIABLE FOR ANY CLAIM, OR ANY DIRECT, SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM ANY ALLEGED INFRINGEMENT OR ANY LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR UNDER ANY OTHER LEGAL THEORY, ARISING OUT OF OR IN CONNECTION WITH THE IMPLEMENTATION, USE, COMMERCIALIZATION OR PERFORMANCE OF THIS INTELLECTUAL PROPERTY.

This license is effective until terminated. You may terminate it at any time by destroying the Intellectual Property together with all copies in any form. The license will also terminate if you fail to comply with any term or condition of this Agreement. Except as provided in the following sentence, no such termination of this license shall require the termination of any third party end-user sublicense to the Intellectual Property which is in force as of the date of notice of such termination. In addition, should the Intellectual Property, or the operation of the Intellectual Property, infringe, or in LICENSOR’s sole opinion be likely to infringe, any patent, copyright, trademark or other right of a third party, you agree that LICENSOR, in its sole discretion, may terminate this license without any compensation or liability to you, your licensees or any other party. You agree upon termination of any kind to destroy or cause to be destroyed the Intellectual Property together with all copies in any form, whether held by you or by any third party.

Except as contained in this notice, the name of LICENSOR or of any other holder of a copyright in all or part of the Intellectual Property shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Intellectual Property without prior written authorization of LICENSOR or such copyright holder. LICENSOR is and shall at all times be the sole entity that may authorize you or any third party to use certification marks, trademarks or other special designations to indicate compliance with any LICENSOR standards or specifications. This Agreement is governed by the laws of the Commonwealth of Massachusetts. The application to this Agreement of the United Nations Convention on Contracts for the International Sale of Goods is hereby expressly excluded. In the event any provision of this Agreement shall be deemed unenforceable, void or invalid, such provision shall be modified so as to make it valid and enforceable, and as so modified the entire Agreement shall remain in full force and effect. No decision, action or inaction by LICENSOR shall be construed to be a waiver of any rights or remedies available to it.


 

i. Abstract

This OGC® Standard specifies standard encoding representations of movement of geographic features. The primary use case is information exchange.

ii. Keywords

ogcdoc, ogc document, moving features, gml

iii. Submitting organizations

The following organizations submitted this Document to the Open Geospatial Consortium (OGC):

Central Research Laboratory, Hitachi Ltd.
Center for Spatial Information Science, The University of Tokyo
Defense Systems Company, Hitachi, Ltd.

iv. Submitters

All questions regarding this submission should be directed to the editor or the submitters:

Name Representing OGC member
Akinori Asahara Central Research Laboratory, Hitachi Ltd. Yes
Ryosuke Shibasaki Center for Spatial Information Science, The University of Tokyo Yes
Nobuhiro Ishimaru Defense Systems Company, Hitachi Ltd. Yes
Hiroshi Kanasugi Center for Spatial Information Science, The University of Tokyo Yes
David Burggraf Individual Yes
Gianluca Luraschi EMSA (European Maritime Safety Agency) Yes
Frank Suykens Luciad Yes
Chris Little UK Met Office Yes
Nadeem Anjum Google Summer of Code representative through Apache No
Martin Desruisseaux GEOMATYS Yes
Ki-Joune Li Pusan National University Yes

v. Changes to the OGC® Abstract Specification

The OGC® Abstract Specification does not require changes to accommodate this OGC® standard.

vi. Foreword

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights. However, to date, no such rights have been claimed or identified.

Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.

OGC Moving Features consists of the following parts under the general title Moving Features Encoding:

-      Part I:XML Core

-      Part II:Simple CSV

 

vii. Introduction

Applications using moving feature data, typically representing vehicles or pedestrians, are rapidly increasing. Innovative applications are expected to require the overlay and integration of moving feature data from different sources to create greater social and business value. Examples of applications that require integrated simulation are disaster risk management, traffic information services, security services, navigation for robots, aviation or maritime traffic monitoring, and wildlife tracking and conservation. Moreover, systems relying on single-source moving feature data are now evolving into more integrated systems. Integration of moving feature data from different sources is a key to developing more innovative and advanced applications.

 Efforts in this direction therefore should be encouraged by ensuring smoother data exchange because handling and integrating moving feature data will broaden the market for geo-spatial information such as Geospatial Big Data Analysis. ISO 19141:2008 is an existing abstract standard to model moving features; however encoding method is not provided.

Therefore, an XML (and GML) style encoding for Moving Features is standardized. The defined encoding standard is ISO 19141:2008 Geographic Information – Schema for Moving Features compliant implementation standard applicable for massive data handling.  ISO 19141:2008 defines a method to describe the geometry of a feature that moves as a rigid body.


1. Scope

This OGC® Standard specifies an encoding format to describe the geometries of many features that move as rigid bodies. This OGC Standard is applicable to features having the following characteristics.

  1. Each moving feature can be described with Schema for Moving Features (ISO19141: 2008).
  2. The number of features simultaneously encoded with this format can be massive (many thousands of features).
  3. All features can be described using common space-time coordinates.

This standard does not address all types of moving features. Examples of features that are out of scope include the following:

  1. Deforming features, such as flood water.
  2. Feature’s geometric representation should not be encoded inline in a geometric complex that contains the geometric representations of other features, since this would require the other features’ representations to be updated as the feature moves.

This standard is focused on the encoding format, thus Web interface and inertial data models are out of scope also.

2. Conformance

Conformance with this specification shall be checked using all the relevant tests specified in Annex A (normative).

3. Normative References

The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of OGC Moving Features. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of OGC Moving Features are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.

[OGC 07‑036] OGC 07‑036, OpenGIS® Geography Markup Language (GML) Encoding Standard
[ISO 19141:2008] ISO 19141:2008, Geographic information – Schema for moving features
[IETF RFC 2396] IETF RFC 2396, Uniform Resource Identifiers (URI): Generic Syntax. (August 1998)
[W3C XML] W3C XML, Extensible Markup Language (XML) 1.0 (Third Edition), W3C Recommendation (4 February 2004)
[W3C XML Namespaces] W3C XML Namespaces, Namespaces in XML, W3C Recommendation (14 January 1999)
[W3C XML Schema Part 1] W3C XML Schema Part 1, XML Schema Part 1: Structures, W3C Recommendation (2 May 2001)
[W3C XML Schema Part 2] W3C XML Schema Part 2, XML Schema Part 2: Datatypes, W3C Recommendation (2 May 2001)

4. Terms and Definitions

For the purposes of this document, the following terms and definitions apply.

4.1 Moving feature

representation, using a local origin and local ordinate vectors, of a geometric objectat a given reference time

 [ISO 19141:2008]

dt class="term">4.2 Foliation

one parameter set of geometries such that each point in the prism of the set is in one and only one trajectory and in one and only one leaf

[ISO 19141:2008]

4.3 geometric object

spatial object representing a geometric set

[ISO 19107:2003]

4.4 leaf

<one parameter set of geometries>

geometry at a particular value of the parameter

[ISO 19141:2008]

4.5 trajectory

path of a moving point described by a one parameter set of points

[ISIO19141:2008]

4.6 one parameter set of geometries

function f from an interval t ∈ [a, b] such that f(t) is a geometry and for each point P ∈ f(a) there is a one parameter set of points (called the trajectory of P) P(t) : [a, b] →P(t) such that P(t) ∈ f(t)

[ISO 19141:2008]

4.7 prism

<one parameter set of geometries>

set of points in the union of the geometries (or the union of the trajectories) of a one parameter set of geometries

[ISO 19141:2008]

4.8 period

one-dimensional geometric primitiverepresenting extent in time

[ISO 19141:2008]

4.9 point

0-dimensional geometric primitive, representing a position

[ISO 19107:2003]

4.10 geometric primitive

geometric object representing a single, connected, homogeneous element of space

[ISO 19107:2003]

4.11 vector

quantity having direction as well as magnitude

[ISO 19123:2005]

5. Conventions

5.1 Abbreviated terms

The following symbols and abbreviated are used in this standard;

ISO
     International Organization for Standardization
OGC
     Open Geospatial Consortium
UML
     Unified Modeling Language
XML
     Extensible Markup Language
1D
     One Dimensional
2D
     Two Dimensional
3D
     Three Dimensional
CSV
     Comma Separated Values

5.2 UML Notation

The diagrams that appear in this standard are presented using the Unified Modeling Language (UML) static structure diagram.  The UML notations used in this standard are described in the diagram below.

UML notation
UML notation

 

In this standard, the following three stereotypes of UML classes are used:

  1. <<Interface>> A definition of a set of operations that is supported by objects having this interface.  An Interface class cannot contain any attributes.
  2. <<DataType>> A descriptor of a set of values that lack identity (independent existence and the possibility of side effects). A DataType is a class with no operations whose primary purpose is to hold the information.
  3. <<CodeList>> is a flexible enumeration that uses string values for expressing a list of potential values.

In this standard, the following standard data types are used:

  1. CharacterString – A sequence of characters
  2. Integer – An integer number
  3. Double – A double precision floating point number
  4. Float – A single precision floating point number

5.3 XML Namespaces

All components of the Moving Feature XML schema are defined in the namespace with the identifier “http://www.opengis.net/movingfeatures/1.0”, for which the prefix mf or the default namespace is used within this Standard.

6. Data Model Overview

6.1 Concepts and standard modularity

Figure 1 illustrates the standard components for encoding and communicating Moving Features data.  The four boxes drawn in the figure portray the four modules defined in the OGC® Moving Features standard.

OGC® Moving Features Simple CSV Encoding and Simple Binary Encoding are fundamental and are data formats to describe moving points and their trajectories. The formats are designed to encode trajectories of moving points compactly as application schemas of IETF RFC 4180 (CSV), NetCDF Discrete Sampling Geometry and so on.

OGC® Moving Features Core, defined in this document, is represented by an XML data encoding for moving points and their trajectories. The format is an extensible format to model and encode movement data for features encoded as point geometries .

OGC® Moving Features 1D/2D Geometry and OGC® Moving Features 3D Geometry are defined to encode moving features that have more complex geometries.

Two UML packages are defined in ISO 19141:2008 [ISO 19141:2008]: “Geometry Types” and “Prism Geometry”.  “Geometry Types” defines the description model of movements including the paths. “Prism Geometry” defines the moving geometry. The two squares drawn with broken lines in Fig. 1 correspond to these packages. The square labeled as “<<Prism Geometry>>” is an implementation of “Prism Geometry”; the square labeled as “<<Geometry Types>>” is an implementation of “Geometry Types.”

OGC® Moving Features modularity
Figure : OGC® Moving Features modularity

 

6.2 Foliation and prisms

Figure 2 illustrates the concepts of foliation, prism, trajectory, and leaf, which are defined in ISO19141:2008[ISO 19141:2008]. In this illustration, a 2D rectangle moves and rotates. Each representation of the rectangle at a given time is a leaf. The path traced by each corner point of the rectangle is a trajectory. The set of points contained in all of the leaves, and in all of the trajectories, forms a prism. The set of leaves also forms a foliation.

The prism of the moving feature can be viewed as a bundle of trajectories of points on the local engineering representation of the feature’s geometry. If viewed in a 4 dimensional spatio-temporal coordinate system, the points on the feature at different times are different points.

  Foliation, prism and trajectory
Figure :   Foliation, prism and trajectory

 

6.3 XML Implementation

An XML data encoding is defined in this standard for implementing the foliation data model. Note that massive amounts of moving feature data may need to be described with this format. Therefore, the data encoding should be compact and easy to handle. Figure 3 illustrates an importing process for a document written in the XML data format. When dealing with massive numbers of moving features, the entire data set may not be able to be loaded into memory. Therefore, the XML data should be parsed on-the-fly. This means that all information needed for interpretation of the XML data should appear at the head of the document. Thus, the XML document written has two main parts: header part and body part. The header part, which is implemented as meta elements, includes meta information for the XML data. The body part, which is implemented as foliation elements, includes the movement information for moving features.

XML parsing
Figure : XML parsing

6.4 Time ordered encoding

Figure 4 shows an example for trajectories of three moving points A, B and C. Each trajectory has the start time and the end time. At t=0 (start of all data), all points start moving. Then, at t =1, the movement of A is changed. In the case, the trajectory of A from t=0 to t=1, the trajectory of A from t=1 to t=2, the trajectory of B from t=0 to t=2, and the trajectory of C from t=0 to t=2 are encoded. This means that only changes of state, including moving-speed, direction, existence, and attributes, are encoded in the format. The encoded changes of state are ordered by time in order to determine the states of all features even if only the first half of data is loaded.

 

Example of trajectories
Figure : Example of trajectories

7. Root Element

7.1 mf:MovingFeatures

7.1.1 Structure

 
  <mf:MovingFeatures
  gml:id=”ID”>
     <mf:sTBoundedBy> ...   </mf:sTBoundedBy>[1]
  <mf:member> ...   </mf:member>[0,..,n]
  <mf:Header> ...   </mf:Header>[0,1]
  <mf:Foliation> ...   </Foliation>[0,1]
  </mf:MovingFeatures>
 
Superclass: gml:AbstractFeature [OGC 07‑036]

 

7.1.2 Description

The root element is named mf:MovingFeatures. The mf:MovingFeatures element consists of mf:sTBoundedBy, mf:member(optional), mf:Header and mf:Foliation. The mf:sTBoundedBy states the spatio-temporal bound of the trajectories.  The mf:Header element has meta-information about the moving features, for example, attribute definition. The mf:Foliation element, which is the main part of the moving feature data, contains moving geometries.

Requirement 7.1 (req/xmlcore/movingfeatures)
The root element shall be mf:MovingFeatures.

The class diagram of the mf:MovingFeatures is shown below.