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Electronic Charts - Standards

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 Electronic charts - purposes

Electronic navigation charts is a source of highly reliable cartographic information that should increase safety of navigation and facilitate everyday mariner's work.

 History of electronic cartography

First electronic charts and related systems had appeared on the market in earlier 80-s. These charts were merely scanned and digitized paper chart reproductions - so-called raster electronic charts.

The quality and contents of nautical charts is the cornerstone of safety at sea, and is strictly controlled by international agreements. Thus, the industrial development of technically elegant solutions is not enough, the products must meet a well defined standard for international approval. To establish such a standard was a long term of IMO/IHO committee work. As a result an international S-57 standard has been established.

 ENC advantages

Comparing to traditional paper chart, electronic charts (especially vector ones) present a number of advantages:

  • in addition to cartographic data borrowed from paper charts, ENC includes information from other sources such as List of Lights and sailing directions. These are no need to look through a number of books searching for required information - all data is already gathered in ENC and may be easily used by a mariner;

  • vector structure of information allows maximum possible automation of navigation safety control - an ECS using vector chart data automatically detects cases of possible danger and informs mariner;

  • updating of electronic charts is simple at the most and may be done in a minutes directly at sea.

  • combined with modern navigation devices, an ENC enables real-time displaying of ship's position course, speed and track, radar and AIS targets movement with the highest possible accuracy.

 S-57 basics

S-57 is a set of regulations approved by IMO and IHO (the international organizations responsible for the safety at sea requirements and related cartography) for standardization of cartographic data exchange between Hydrographic Offices,  Regional Chart Distribution and ECDIS-producers.

S-57 chart comprises data of two sort - spatial (location information about real world entities) and feature (descriptive information about real world entities). Data in S-57 data set (chart) is organized in objects. Spatial objects (e.g. node, edge, face) possesses coordinates which define its location on the Earth's surface. Feature object (e.g. BOYCAR - buoy cardinal, COALNE - coast line, LNDARE - land area) contains attributes - qualitative or quantitative characteristics of the object. Object may reference each other that enables simulation of arbitrary level of complexity. Detailed information on S-57 may be found in IHO Transfer Standard for Digital Hydrographic Data Edition 3.0 - March 1996. Special Publication No 57.

To browse IHO S-57 / ENC - Object and Attribute Catalogue online click here.

At the present moment there is a transition from the old S-57 version 2 (also known as DX90) standard specification to its last issue named S-57 version 3.

 S-57 and SENC

It is notable that 'native' S57 data is a format which is designed for the exchange or transport of chart data between the Hydrographic Offices was not intended for direct presentation of charts on a computer screen. Instead, an internal and more compact 'SENC' format may be used.

One of the most widespread SENC formats is CM93/2 from C-Map. CM93 vector charts provides worldwide coverage by high-quality vector cartographic data.

All dKart electronic navigation chart systems - dKart Navigator, dKart Explorer and dKart Catalogue PRO - may handle both S-57 official data and CM93 charts.

For more information about CM93 chart, please refer to electronic charts page.

Additional topics related to the electronic cartography may be discussed at dKart Online Forum.


Additional topics related to the electronic cartography may be discussed at dKart Online Forum.

Morintech Navigation AS
Hovlandsveien 52 P.O.Box 212
N-4379 Egersund Norway
phone +47 51 464930
fax +47 51 464701

Morintech Navigation AS 1999-2000

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