Simple Features SWG


Herring, John (Herring, John) - Group Chair

Group Description:


1.    ISO Simple Features

A Standard working group is being formed to work on the ISO version of the Simple Features specification. The intent is to create a fully harmonized standard so that the OGC and ISO standards and the SQL/MM Part 3 spatial versions are harmonized at the end of the work of the  SWG. A summary SWG description is given here and expanded below:


ISO 19125: Simple Features


Update the ISO 19125 (OGC) Simple Features standard to

  • Maintain and correct the current standard
  • Factor out independent modules such as:

o   Well known text

o   Well known binary

o   Spatial operators (9-DIM, Egenhofer, Clementini, RCC-8, RCC-16

  • Synchronize with SQL/MM: Part 3 Spatial,
  • Introduce new geometry types,
  • Support 3D coordinates, and
  • Linear reference systems including segmented attributes.

All documents submitted to a vote in OGC will also be submitted as an NWIP to ISO TC 211. No standard will be published by either ISO or OGC until both communities have approved the same version of the normative text.


IPR Policy:

Royalty free, RAND


  • Corrigendums for current Common Architecture and SQL Option, possibly factored, but maintain 1.1 conformance as core conformance tests (as given currently and in the past)
  • Extensions for the new geometry types
  • Extension for 3D and parameterized coordinate reference systems
  • Extension of 3D coordinates
  • Extensions for query for 3D geometries and linear reference systems

2.    Purpose of the Standards Working Group

The purpose of the ISO 19125 SWG will be to update the common standard that is both the OGC Simple Features Implementation Standard and the ISO 19125 Standards (Part 1: Common Architecture, and Part 2 SQL Option) to:

  • Maintain and correct the current standard
  • Synchronize with SQL/MM: Part 3 Spatial,
  • Introduce new geometry types,
  • Support 3D coordinates, and
  • Linear reference systems including segmented attributes.

Note: It has been argued that merely re-writing the current version of Part 1 is a short-term expedient that does nothing to insure the harmonization of SFSQL, SQL/MM and GML. A position paper has been introduced by Paul Scarponcini that argues for a new Part 1 that can serve as a common Logical Model for these and other subsequent encoding standards. 

Therefore, the first order of business of this SWG should be to consider this position paper.

3.    Scope of Work

The scope of the Simple Features project is to define:

1.      An unrestricted feature model consistent with ISO 19109: Rules for application schema and ISO 19110: Methodology for feature cataloguing.

2.      A commonly agreed to layering of the geometries associated to ISO 19107: Spatial schema beginning with the simplest and adding complexity as the community matures, defining the minimal sets of geometric representations for use in the geographic information communities

This layering begins with 2D coordinate reference systems and extends into 3D systems and linear referencing systems. It begins with simple linear or planar interpolation algorithms, and then adds circular, conic and will eventually include complex spline functions (polynomial, rational, Bézier, NURBS).

Each level in this structure will be related to a conformance class. Each conformance class will be a platform for the ones above it and an extension of the ones below it. Emphasis will be on interoperability within a common conformance class but also include mechanisms for interoperability across conformance classes.

3.1    What is out of scope?

Any restrictions on other aspects of feature schemata are out of scope.

3.2    Existing Work as a Starting Point

This work will all derive from the ISO TC 211 body of work (ISO 191xx standards), from the OGC abstract specification and from the work in ISO/IEC JTC1 on Multimedia and Application Package extensions to SQL. More specifically, the following standards will be heavily referenced[1]:

From ISO TC 211 often in cooperation with OGC

ISO 19107:2003  Spatial schema

ISO 19109:2005  Rules for application schema

ISO 19110:2005  Methodology for feature cataloguing

ISO 19111:2007  Spatial referencing by coordinates

ISO 19111-2:2009  Spatial referencing by coordinates - Part 2: Extension for parametric value

ISO 19125-1:2004 Simple feature access - Part 1: Common architecture

ISO 19125-2:2004 Simple feature access - Part 2: SQL Option

ISO 19136: Geographic markup language (GML)

ISO 19148: Linear Referencing (currently in DIS)


ISO/IEC 13249-3:2006 SQL multimedia and application packages -Part 3: Spatial

3.3         How it is to be Determined when the Work of the SWG has been Completed

The work of the SWG will be done when all of the items in Clause 1 above have been incorporated in documents and those documents have been passed as standards by both ISO and OGC.

4.    Description of deliverables

This scope involves several activities, to maintain, correct and extend the current standards. This current specification consists of two parts:

Part 1: Common Architecture

Part 2: SQL Option

The deliverables for this SWG will consist of (at least):

1.      Corrigendums or new drafts for current Common Architecture and SQL Option

2.      Extensions for any items pulled from this earlier parts as a modularization mechanism, possibly including:

a.       Well-know text

b.      Geometric operations (boundary, convex hull, buffer, etc.)

c.       Boolean query operators such as the Egenhofer, Clementini, RCC 8, RCC 16, WithinDistance, etc.

3.      Extensions for the new geometry types, especially for those introduced in SQL/MM (ISO/IEC 13249-3:2006)

4.      Extension for 3D and parameterized coordinate reference systems, for consistency with ISO 19111

5.      Extensions for linear reference systems (ISO 19148)

6.      Extensions for query for 3D geometries and linear reference systems

This section describes what the deliverables will be for this SWG activity. Deliverables could be a revision to an existing standard, including revisions to schemas. A deliverable could also be a best practices document.

This section also includes a preliminary schedule of activities. For example, an RFC focused SWG schedule would provide a plan and schedule that includes the start date, target date for release of the candidate standard for public review, date for consolidation of comments, date for edits to document based on comments, and a final target date for making a recommendation to the Membership. This information will be made public and will be used as input to a RoadMap for the document. Therefore, the more detail the better.

5.    IPR Policy for this SWG

The IPR Policy for the Simple Feature SWG will be RAND and Royalty Free.

6.    Anticipated Audience

The primary audience for the Simple Feature standards will be anyone implementing common database, data storage or data transfer mechanisms designed for multiple application support. For this reason, the common Architecture facet of the SWG will concentrate on implementation-independent data content and representation-independent data access protocols. When a protocol or data structure is used, every effort will be made to choose one that is well accepted, easy to use and implementable by a wide variety of encodings such as SQL and GML.

Ease of use and ease of understanding will be the two most important requirements of the Simple Features work.

7.    Other informative information about the work of this SWG

7.1    Similar or applicable standards work (OGC and elsewhere).

The following standards and projects may be relevant to the SWG's planned work, although none currently provide the functionality anticipated by this committee's deliverables:

  • ISO 19107:2003 Spatial schema
  • ISO 19125-1:2004 Simple feature access - Part 1: Common architecture
  • ISO 19125-2:2004 Simple feature access - Part 2: SQL Option
  • ISO 19136: Geographic markup language (GML)
  • ISO/IEC 13249-3:2006 SQL multimedia and application packages -Part 3: Spatial

The SWG intends to seek and if possible maintain liaison with each of the organizations maintaining the above works. This will include ISO TC 211 and ISO/IEC JTC1 SC32 WG4


7.2    Details of the first meeting

The first meeting of the committee will be held by telephone conference call at -AM EDT on - May 2010. Call-in information will be provided to the SWG's e-mail list and on the portal calendar in advance of the meeting.

7.3    Projected on-going meeting schedule

The work of the committee will be carried out primarily by email and conference calls, possibly every two weeks, with face-to-face meetings perhaps during each of the OGC TC meetings.

7.4    Supporters of the Proposal


The following people support this proposal and are committed to the Charter and projected meeting schedule.

John R. Herring

john.herring [at]

Oracle America

Olivier Courtin

olivier.courtin [at]


Jan Herrmann

herrmanj [at]

Technische Universität München, Dept. of Informatics

Paul A. Birkel

pbirkel [at]

MITRE Corporation


7.5    Convener

Name of individual who started the SWG process. Could be the lead for an RFC submission, an OGC staff person or an individual who believes it is time for a revision to an adopted standard.


[1] Undated References mean that more than one version of a document may be used in different conformance classes