IHO 2003

2003 National Report for IHO

 

 

ICA Commission on Spatial Standards

4-7 August 2003 – Ithala, South Africa

IHO Report on Standard Development

Michael Huet

International Hydrographic Bureau

Monaco, France

July 2003

IHO geographic information standardization work mainly relates to electronic charting and relevant standards are contained in the following two IHO publications:

  • S-52 “Specifications for Electronic Chart Display and Information Systems (ECDIS)”. Of particular interest is the IHO standard for display of Electronic Navigational Charts (ENC) on ECDIS.
  • S-57 “Transfer Standard for Hydrographic Data”. This standard includes a product specification for ENC.

Current work aims at preparing new editions of S-52 and S-57, which will have significant improvements from the existing editions.

  1. S-52 – New editions of the IHO Colour and Symbol Specifications for ECDIS and the IHO ECDIS Presentation Library are planned for October 2003.

Important new issues included in the new editions:

  • Inclusion of all amendments made since the previous editions (1997);
  • Revised conditional symbology procedures;
  • Colour calibration procedures for flat panel displays;
  • Substitution of the existing five colour table model by an improved, easier to use three colour table model;
  • Paper based description of symbols contained in the IHO Presentation Library;
  • Digital Chart 1 of ECDIS symbols for onboard use in tiff format,
  • Series of chart plots showing symbology of the IHO Presentation Library, based on IEC[1] Test Data Set for ECDIS.

          In view of the subsequent edition of S-52 (2005/2006), the IHO will initiate investigations on:

  • How to transform the IHO Presentation Library notation to become compliant with ISO 19117 (see also Portrayal under 2. below), and
  • What could be potential presentation aspects of bathymetric data to be standardised?

  1. S-57 – A new edition of the IHO Transfer Standard is planned for 2005/2006. It is intended to make it consistent with the ISO 19100 series of standards, as far as possible, and this implies that the latter standards be first published.

Preparation of the new edition is progressed through specialized work items, as follows:

Object Catalogue – A model for a data dictionary, with object classes, attributes and attribute values, is being developed, which will fulfill the requirements for a registry, as standardized by ISO/TC211. An XML implementation of the existing IHO Object Catalogue is also being prepared. As regards the registration procedure, two registers will be maintained within the IHO registry, one for the IHO hydrographical features, and another for supplementary hydrographical features.

ENC Product Specification

One of the major concerns at present is the inconsistency in ENCs created by different nations.  In many cases, the current edition of S-57 provides encoding choices, resulting in some cases in complex conditional symbology procedures within the IHO Presentation Library and of poor quality ENCs being displayed on some type approved ECDIS.  It is considered that there is an urgent need to sort out issues of scale ranges for navigational purposes, the use of compilation scales within ENCs and how SCAMIN (attribute giving the scale beyond which the attributed object will not be displayed) is used.  Additional work to be commenced in the shorter term will include developing a mechanism to contain the data dictionary for ENCs, reviewing constrains that need to be applied at the attribute value level for ENCs, and following the work of ISO 19131 to ensure compatibility with the future ENC product specification.

Imagery and Gridded Data (IGD)

The initial three ISO/TC211 work items of interest to IHO are:

  • 19123 Coverage Geometry and Functions – describes geometry of grid, point set and coverage;
  • 19129 Imagery and Gridded Data Framework – new components (19115-2 metadata & 19101-2 reference model);
  • 19130 Sensor and Data Models – will help define required sensor metadata.

Actions planned will include:

  • Selecting possible structures (e.g. Regular Rectangular Grid, Irregular Grid, TIN);
  • Submitting to ISO 19127 the current IHO list of Geodetic Codes and Parameters, as in the S-57 Object Catalogue;
  • Imagery encoding to consist of XML metadata (19118 – neutral encoding of metadata) and JPEG 2000;
  • Gridded Data encoding to consist of XML metadata (19118) and a neutral array definition, possibly NetCDF;
  • Reviewing 19115-2 and creating a profile for Imagery and Gridded Data.

3D & Temporal Data

Time only needs to be included as an attribute (as defined by ISO 19108). Vector geometry in 3D will be as per 19107, with no need for topology. The following seven gridded data building blocks are being considered: grid point attribution; quadrilateral grid structure; variable pixel size & sub-grids; multiple grid ordering; sparse grids; re-gridding/interpolation methods; and feature object grids with fields and masks (meta-objects).

Metadata

Taking into consideration that ISO 19115 on metadata for vector data is now at the FDIS stage, that the existing XML DTD (Document Type Definition) for ISO 19115 has been replaced with an XML Schema, bringing it into line with other ISO/TC211 publications, and that a new TC211 work item dealing with raster gridded and coverages metadata has been proposed, to be published as ISO 19115 Part 2, IHO activities on metadata, completed or planned, include:

  • A database containing a data dictionary for metadata elements has been developed and populated with 19115 metadata elements. This will be used for adding extra hydrographic elements, and for generating the S-57 metadata dictionary documentation.
  • A cross mapping between ISO 19115 and S-57 had been undertaken.
  • A list of metadata elements for hydrographic survey requirements had been produced. It will be complemented with tidal metadata elements.

Base Documents

This work item includes developing a Spatial Profile, with geometry and topology object classes being included, a Coordinate Reference System, and a General Feature Model / Application Schema.

Hydrographic Survey Content Specification

Initial steps in process will be:

  • compile a list of all known hydrographic/bathymetric standards;
  • refine the list of products/applications from “all possible” down to “more reasonable”, e.g. field/fair sheet, bathymetric maps, sea-floor classification, UNCLOS, by products of multi-beam survey (e.g., backscatter imagery);
  • review the relevant ISO/TC211 standards required to produce a hydrographic survey application profile; and
  • determine what metadata items are necessary.

Portrayal

This term relates to the ENC presentation rules on ECDIS, as defined in S-52. These rules are strictly based on the ENC product specification and any future portrayal definitions compliant with ISO standard 19117 would need new or revised product specifications based on an ISO standardised data format as well.  The IHO has noted that the general schema contained in ISO 19117 is very similar to the general construction of the IHO Presentation Library (PL). Specific terms of S-52 are equivalently expressed in ISO 19117 with generic terms Objects being called Features, Look-up tables being called Portrayal catalogues, Conditional Symbology Procedures being called Portrayal rules, etc. Beyond those similarities ISO 19117 introduces the use of:

  • OCL – Object Constraint Language. OCL is defined to be used for the interface to the data format, whereas the IHO PL is based on the current structure of the ENC Product Specification.
  • UML – Unified modelling language for the description of interface to the data format and presentation procedures. UML is defined to be used for the description of interrelations and dependencies, whereas the IHO PL uses alternative methods for this purpose, i.e. Nassi-Schneiderman diagrams and textual descriptions.

Taking into account of the compelling need to adapt current presentation rules to ISO standard 19117 in future, it is intended to begin the transformation of selected items of the current IHO PL to ISO 19117 notation in order to gain familiarisation with this process.

Paper Chart Product Specification

The tasks are to investigate required specifications and develop, or extend, standards for:

  • The exchange of digital repromats for paper charts, allowing one chart producer to receive paper chart data from another chart producer for the purpose of reproduction.
  • Create paper charts from an S-57 database allowing chart producers to create paper chart from the same data that is used for ENC production, and to limit the amount of cartographic work required during the paper chart compilation phase.

A draft co-operative agreement between ISO/TC211 “Geographic Information / Geomatics” and the IHO was submitted for consideration to the 16th TC211 meeting, Thun, Switzerland, 19-23 May 2003. As a result, TC211 has instructed the ISO secretariat to review the proposal in cooperation with the ISO Central Secretariat and forward the final text of the cooperative agreement for approval by the ISO Council (Resolution 256).

© Copyright, ICA Standards Commission, 2003