Raster V. Vector — the battle continues

The relentless advance of new technology continues to force change in one of the world's oldest and most conservative of activities, the marine industry.

Navigation at sea has been developed over thousands of years. Probably — until recent times — its most important advance was the chronometer making possible the calculation of longitude. But even this momentous event is being overshadowed by the development of electronic navigation concepts. Not least among these is ECDIS — electronic chart display and information systems.

There are currently two types of accepted electronic charting systems. Raster and Vector.

Raster charts are more easily produced than those using the vectorized principle, which involves producing data in layers laid progressively on top of each other.

One of the major advocates of raster charts is the U.K.

Hydrographic Office (UKHO), whose systems can transpose its paper chart portfolios to raster scan products, capable of being used by approved electronic chart systems under its ARCS service. This has initially provided the marine industry with an acceptable electronically digitized format, but lacks the versatility of the vectorized chart.

The U.K. Hydrographic Office (UKHO) said that it does not take a position favoring raster or vector charts — providing they are officially authorized — but sees great benefit from combining the two systems for a complete, worldwide coverage.

The compilation of a vectorized chart is a time-consuming and lengthy process and production is being concentrated on high-risk areas such as coasts and harbors, leaving the deep sea and ocean passage routes to be covered by View from the cockpit .. the control bridge on the Stena HSS. The captain and co-pilot/navigator sit in aircraft-type chairs and have access to all necessary information via three computer screens immediately in front of them.

raster scanned charts for the immediate future.

It has taken a number of years for an international standard to approach ratification under the auspices of IMO working with the International Hydrographic Offices (IHO).

The UKHO has been actively involved in the development of international standards for electronic navigational charting (ENC) and ECDIS, working closely with the Monaco-based IHO.

Towards this end the UKHO has been a member of a working group set up to develop the protocol for electronic charts, Special Publication 57, more commonly known as S57, the transfer standard for digital hydrographic data, and also the product specification for ENC. These two documents define the content and format of official ENC data sets and have therefore been essential to the establishment of an ENC service. Edition 3.0 of S57 was agreed in February 1996, followed by a period of final study. In November 1996 this international standard was fixed for four years to allow equipment manufacturers to produce ECDIS equipment, and hydrographic offices to get ENC to a stable environment.

The UKHO has been producing prototype ENC data for several years in S57 Edition 2.0 format, covering selected limited areas, in support of ECDIS sea trials. This has been mainly concentrated on the Baltic and North Sea and included the ECDIS Testbed (BANET) project, which involved the use of the high-speed ferry Finnjet on its Baltic Sea route and later onboard the car ferry Hamburg, operating between Harwich, U.K. and Hamburg, Germany.

This latter project was mainly concerned with the updating of ENC data onboard the ship for the equivalent of four paper charts. Some of this updating was achieved while the vessel was at sea using a shore-based bulletin board which the vessel could access via cellular telephone system. Another trial was conducted onboard the buoy tender Pharos using charts based on Oban harbor in northwest Scotland.

A future trial of ECDIS is planned aboard a ferry operating between Rotterdam in The Netherlands and Hull, U.K. for which the Norwegian Electronic Chart Center (ECC) and the UKHO are providing the data. This trial was originally scheduled for early 1996 with the UKHO providing S57 Edition 2.0 data, but with adoption of Edition 3.0, it has been rescheduled to use the later information. According to the UKHO, updating Edition 2.0 data to the new protocol requires considerable skilled manual intervention and, in some instances, it is better to ignore the earlier edition and start afresh using the Edition 3.0 standard.

The collaboration of the UKHO and ECC is speeding the establishment of a regional ENC database and to jointly market a service as a Regional Electronic Chart Coordinating Center (RENC). This is in accordance with the IHO's World Electronic Navigational Database (WEND) principles. The two organizations are cooperating with other European HOs in building a single, integrated ENC database for the region. The service will provide both ENC chart data with full updating procedures.

As a premium product, said the UKHO, it is expected to be of particular interest to those maintaining the tightest schedules, high value vessels, passenger ships and those carrying hazardous cargoes, which can realize the greatest benefit from improved safety. The RENC service will be undertaking a trial service this year.

Additional collaboration between European HOs is demonstrated by the Electronic Chart Hub Organization (ECHO) project which is an approved scheme of the EU's Telematics Program.

This is designed to develop and demonstrate the supply of validated ENC data and meta-data (associated administrative data) from HOs to a RENC, the integration of the data with the RENC and the distribution of the ENC data to vessels at sea, fitted with the appropriate ECDIS equipment, making use of telecommunications technology throughout.

The participants in the project are the ECC as the RENC, the U.K. and Finnish hydrographic offices as supplying HOs, the Finnish Maritime Authority as receiving vessels, and the following software houses: Iona, Ireland and Sysdeco Dikas, Norway. Aspo in Finland is the nominated ECDIS manufacturer while Inmarsat and Telenor are the communications authorities.

Also involved is Sintef of Norway as a research organization. Started in early 1996, the project is expected to last two years.

Work is well underway in production of prototype data and the UKHO, in conjunction with other regional HOs which are supplying source data, has now fully developed its production capability to capture and convert chart data into an ENC database. The production program is generating ENC data for the U.K., in order to provide it to the northern Europe RENC.

The UKHO says there is a clear need for the commercial shipowner to have access to officially approved and updated ENC data, so that ECDIS equipment can be safely used.

In recognition of this situation, the ECC and UKHO are working at full speed to produce an official ENC with an update service covering some commercial routes which will be attractive to potential customers. In order to ensure the correct data has been collated, extensive market research has been conducted with consultations carried out with a wide variety of ship operators with both small and large fleets, and of many nationalities, to ascertain what should be included in the ENC service and which areas should be covered.

The IMO adopted the performance standards for ECDIS in November 1995, and by the end of February 1996 agreement had been reached on both the data transfer standard — S57 Edition 3.0 — and the ENC product specification. The display catalog was finalized in November last year and type approval for ECDIS is expected from the International Electrotechnical Commission (IEC) in 1998.

The ENC database is currently being developed and trials, including a prototype updating service, will be ready by the end of this year, an in 1998 the mariner should have ready access to the safety benefits of ECDIS within some major shipping routes and ports, the information being supplied through the northern Europe RENC.