Electronic Chart Display and Information

Systems

Objectives:

1. Become familiar with the principal types of electronic charts.

2. Understand the difference between an ECDIS and an ECS.

3. Understand the different Electronic Chart formats and their advantages and disadvantages.

Objectives:4. Become familiar with the display characteristics of

an ECDIS System.

5. Understand the limits of an ECDIS based on the performance limits of sensors.

6. Understand the US Navy policy and plan on ECDIS Systems.

7. Understand the risk of over reliance on an ECDIS System.

Background Electronic databases, operating systems, computer technology and the widespread deployment of Digital technology has made it possible to employ electronic charts at sea.In addition, the advent of continuous and automated positioning systems (such as GPS), have made it possible to take maximum advantage of electronic charting.

The benefits of the integrated system GPS and chart data in digital format

include:

- Real time position .- Automated plotting of the navigation. - Reduce Manning - Minimizing Human error .- Alert to navigation dangers. - Dramatically increase awareness in low visibility.

Electronic Charting Systems

Advances in technology have made it possible to replace the traditional paper charts with Electronic Charting Systems.

All electronic charting systems fall into two categories. The two categories are:

• ECDIS (Electronic Charting and Display System) • ECS (Electronic Charting System).

Electronic Chart Display & Information System (ECDIS)

“means a navigation information system which, with adequate back-up arrangements, can be accepted as complying with the up-to-date chart requirements by regulation V/20 of the 1974 SOLAS Convention, by displaying selected information from a system navigational chart (SENC) with positional information from navigation sensors to assist the mariner in route planning and route monitoring, and by displaying additional navigation-related information if required.”

Sec. 2.1 IMO PS

And that means???? The short explanation is an ECDIS is a

system that is able to display electronic chart information with:

- automatic position updates

- built in redundancy

- that will assist the mariner in all aspects of Navigation.

It is the legal equivalent of a paper chart.

It is Not an ECDIS if…..

Equipment is not legally approved. Does not have adequate electronic chart

coverage. Does not have chart updating capability.Even though an ECS may perform many of

the same functions as an ECDIS, it is not the legal equivalent of an ECDIS. It may only be used for “situational awareness”.

What makes up an ECDIS or ECS?

1. Position inputs (GPS, DGPS, LORAN, Radar, gyro, fathometer, etc.)

2. Electronic Navigation Charts (ENC)

3. System Electronic Navigation Charts (SENC)

Color Display

Computer AISGyrocompass

ENCDepthsounder Currents

Updates

Radar/ARPA(GPS, LORAN)Nav Sensors

Water level

Ice info

ECDIS COMPONENTS

SENC

XTD

SPD

CSE

Electronic Navigational Chart (ENC)

“means the database, standardized as to content, structure and format, issued for use with ECDIS on the authority of government-authorized hydrographic offices. The ENC contains all the chart information necessary for safe navigation, and may contain supplementary information in addition to that contained in the paper chart (e.g., sailing directions) which may be considered necessary for safe navigation.”

Sec. 2.2, IMO PS

So What?

An ENC is a database, not a chart as you think of it. As such, there are:

• different types of ENC data

• various formats

• differences in the level of content

System ENC (SENC)

“means the database resulting from the transformation of the ENC by ECDIS for appropriate use, updates to the ENC by appropriate means, and other data added by the mariner. It is this database that is actually accessed by ECDIS for the display generation and other navigational functions, and is the equivalent of an up-to-date paper chart. The SENC may also contain information from other sources.”

Sec. 2.3, IMO PS

ENCENC

Data

Updates

#1

#2

#3

SENC

#1

#3

#2

+

+

+

SENC

SENC

SENC

1

2

3

IHO S-57 Performed in ECDIS

Software

IHO S-52 Colors & Symbols

Display

System Electronic Navigational Chart (SENC)

NextNext

Not all charts are equal….

• Many different formats exist for electronic charts.• The two major types are vector based and raster

charts.• Raster charts are scanned paper charts.• Most vector charts are digitized paper charts,

thereby inheriting any errors (and possibly introducing some!)

• Countries are producing unique digital charts based on their interpretation of IHO standards.

ENC

DNC® BSB

ARCS

C-MAP

Navionics

Transas

The Types of EC Formats are:Raster and Vector

NIMADigital Nautical Chart (DNC®)

IHO S-57Electronic

Navigational Chart(ENC)

NOAARaster Nautical

Chart (RNC)

Digital Chart Formats

The Basic Difference

• Raster charts are simply bitmap images created by scanning a paper chart

• Vector charts portray charted features as points, lines, or areas with amplifying information (attributes) found in an associated database

Raster Charts

• A set of colored pixels representing chart information as a picture on computer screen

• Simply an array of pixels arranged in rows and columns

• Pixels are color coded, but do not represent features explicitly

The Appeal of Raster

• Looks like a paper chart (appeals to traditionalists)

• Cheap and easy to produce (scan existing paper chart)

• Runs easily on PC

• World-wide availability

Vector Charts: More detail

• A set of accurately positioned lines (vectors), points and areas, with associated attributes (e.g. “shoreline”, “buoy - red”) organized in a database accessed by clicking on displayed symbol

Paradigm Shift

• Looks “different” from a paper chart

• Underlying database allows queries and layer selection

• Zooming reveals detail• Complex, expensive, and

time-consuming to produce• Needs more powerful

computer and expensive display to meet IHO/DoD requirements

USN Approach is to use NIMA’s Digital Nautical Chart (DNC), a vector based format.

DNC with Base data only showing (Less clutter)

Standard Display with Depth Contours

The user defines what features are necessary!!!

Standard Display with Spot Soundings

DNC with User defined Color

All Features

Which is better?

• Depends on your point of view….

• Raster is easier and cheaper to produce, but vector provides much more information to the navigator

• DoD standard is Vector Product Format --DNC®

• NOAA BSB charts cover US waters

The Advantages of Vector Charts

• Information on Chart can be linked to specific points. (Click on light and you can retrieve more info, like a picture of the light)

• Allows the user to display the information that is necessary for the ship’s current mission.

Raster Concerns

• High scan resolution required for detailed chart….lot’s of CPU memory required and slower refresh rates.

• Zooming degrades quality.

• Mixed pixels—is it water or land?

Raster Model

Land

Shoreline

Water

Vector Shoreline

US Navy Policy• The Chief of naval Operation ( CNO) issued a directive in march 1998 establishing minimum ECDIS standards (ECDIS-N) and calling for a transition of the entire Navy fleet from paper based charts to electronic digital Chart by FY 2007. This has recently changed to 2004, with the first ECDIS-N certified battlegroup deploying in FY01.• Until then, ships may use an ECS for enhanced situational awareness, but the paper chart must be maintained as well.

USN ECDIS-N Requirements

•Navy standard, automated and continuous positioning systems

•Display of radar, visual and celestial navigation fix information

•Ability to read and display National Imagery and Mapping Agency (NIMA) Digital Nautical Charts (DNCs)

• System-to-system interoperability

The US Navy Approach

• Several Different Programs including NAVSSI (USN), NAVSSI-Lite, and VMS/IBS.

• All programs will use NIMA’s Digital Nautical Charts.

• Most systems will also be able to read raster charts.

ECDIS-N Platforms

169 combatants scheduled for NAVSSI/NAVSSI Lite, including NIMITZ class aircraft carriers, ARLEIGH BURKE class destroyers, TICONDEROGA class cruisers, WASP class amphibious assault ships and Perry class frigates.

Virginia class SSN will employ ECDIS-N software for its Navigation Data Distribution and Display (ND3) system.

13 FAMOUS class cutters. There is potential for installation on other cutters.

Visual Bearing LOP Fix

Radar Range LOP Fix

Piloting Guidance

Automatically calculates:• cross-track error• recommended course to

steer accounting for set/drift

• nearest hazard • next navigation aid• depth • distance and time to turn

Military standard navigation report

Tabular turnpoint solution data

Tide and Current Information

Displayed on the chart…

…and graphically in pop-up windows.

The Risks of ECDIS

• ECDIS is only a tool that helps a mariner safely and effectively navigate a ship.

• It is not the end-all be-all to ship navigation.

• One of the biggest risks with the transition to ECDIS is an over reliance in the information provided

Some things to consider…• Poor GPS performance• DGPS used/not used• ECDIS malfunction• installation setup• ENC compilation errors (e.g., datums)• chart (errors, omissions, out-dated)• survey errors• human error

Any Questions?