INTERNATIONAL HYDROGRAPHIC ORGANIZATION
 
 
 
PRODUCT SPECIFICATION
for
RASTER NAVIGATIONAL CHARTS (RNC)
1st Edition, January 1999
 
 
 
Special Publication No. 61
 
 
published by the
International Hydrographic Bureau

MONACO
 
 
S-61



International Hydrographic Bureau
4, Quai Antoine 1er
B.P. 445 - MC 98011 MONACO Cedex
Principautι de Monaco
Telefax: (377) 93 10 81 40
E-mail: info@ihb.mc
Web: www.iho.shom.fr




 
FOREWORD
In December 1998, the International Maritime Organization's Maritime Safety 
Committee adopted an amendment [IMO resolution MSC.86 (70)] to the then-current 
Performance Standards for Electronic Chart Display and Information Systems 
(ECDIS), adopted by IMO resolution A.817 (19), as amended by IMO resolution 
MSC.64 (67), which are also annexed to IHO Publication S-52.
IMO resolution MSC.86 (70) permits ECDIS equipment to operate in a Raster Chart 
Display System (RCDS) mode in the absence of Electronic Navigational Charts 
(ENC). When operating in the RCDS mode, ECDIS should be used together with an 
appropriate folio of up-to-date paper charts. 
The RCDS mode of operation is described in a new Appendix 7 to the IMO 
Performance Standards for ECDIS. For convenience it is annexed to this 
publication, with the kind permission of the IMO. A key component of the RCDS 
mode is the Raster Navigational Chart (RNC). Section 4.1 of Appendix 7 states 
that the RNC must conform to IHO standards. The necessary RNC Product 
Specification was developed by the IHO's Transfer Standard Maintenance and 
Application Development Working Group (TSMAD) during 1997 and 1998 and was 
adopted by the IHO's Committee on Hydrographic Requirements and Information 
Systems (CHRIS) in October 1998.
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TABLE OF CONTENTS
1. Introduction ................................ 1
2. Definitions ................................. 1
3. RNC Requirements ............................. 1
  3.3 Image Files ............................. 1
  3.4 Meta-Data ................................ 2
  3.5 Updates ............................... 3
Annex A - 
  RCDS Mode of Operation (Appendix 7 to IMO Performance Standards for ECDIS)... 
  A-1 


      1INTRODUCTION
      1.1The elements of this product specification define the minimum 
      requirements a Raster Navigational Chart (RNC) must have to satisfy the 
      draft performance standard for a Raster Chart Display System (RCDS).
      1.2This product specification does not define underlying raster data 
      structures of a raster navigational chart. The national hydrographic 
      office producing the raster navigational chart should select that data 
      structure.
      2DEFINITIONS
      2.1For the purpose of this product specification:
      2.1.1Raster Chart Display System (RCDS) means a navigation information 
      system displaying RNCs with positional information from navigation sensors 
      to assist the mariner in route planning and route monitoring, and if 
      required, display additional navigation-related information.
      2.1.2Raster Navigational Chart (RNC) means a digital facsimile of a paper 
      nautical chart, produced by or distributed on the authority of a 
      government authorized hydrographic office. RNC is used in these 
      specifications to mean either a single chart or a collection of charts.
      2.1.3Notice to Mariners (NtM) means a published change to an RNC produced 
      by or distributed under the authority of a government authorized 
      hydrographic office.
      3RNC REQUIREMENTS
      3.1An RNC should contain an image file, which is a digital facsimile of an 
      existing, official paper chart. It should also contain meta-data 
      describing the RNC as stated in this product specification. 
      3.2The arrangement of the image data and the meta-data into one or more 
      digital files should be determined by the national hydrographic offices 
      originating the RNC.
      3.3Image Files
      3.3.1The digital format of the image file should be determined by the 
      national hydrographic office producing the RNC.
      3.3.2The resolution of the digital image (pixels-per-inch) and any method 
      used to compress or process that image file should be sufficient to 
      display clearly all information that was contained on the original paper 
      nautical chart. In particular, methods such as antialiasing should be 
      employed to achieve maximum contrast and fidelity of displayed chart 
      information compared to the printed chart.
      3.3.3The accuracy of the digital image file, as measured by the ability to 
      determine the correct geographic coordinates of an individual pixel when 
      the image file is used together with the RNC meta-data, should allow a 
      ship’s position to be displayed at least as accurately as when using the 
      original paper chart.
      3.4Meta-Data
      3.4.1The digital format of the meta-data should be determined by the 
      national hydrographic office originating the RNC.
      3.4.2The following meta-data should be included for each RNC. Where an 
      image file contains more than one discrete chart image, e.g. chart insets, 
      in addition to the main panel of the chart the meta-data should be 
      included for each such discrete chart image.
      3.4.2.1Producing agency identifier specified using the producing agency 
      codes listed in Annex A to Appendix A of IHO publication S-57.
      3.4.2.2RNC number.
      3.4.2.3Chart identifier (e.g. chart number) if different from the RNC.
      3.4.2.4RNC edition date.
      3.4.2.5Chart edition date and/or chart edition number.
      3.4.2.6Last update or Notice to Mariners applied.
      3.4.2.7Previous updates or Notice to Mariners applied.
      3.4.2.8Chart Scale.
      3.4.2.9Orientation of north (where appropriate for the chart projection in 
      use).
      3.4.2.10Projection and associated projection parameters.
      3.4.2.11Horizontal datum.
      3.4.2.12Horizontal datum shift to WGS84 or PE-90 if the chart datum is not 
      one of those two datums.
      3.4.2.13Vertical datums.
      3.4.2.14Depth and height units.
      3.4.2.15Pixel resolution of the image file as measured in 
      pixels-per-millimeter or pixels-per-inch.
      3.4.2.16A mechanism, such as parameters and an algorithm, to allow 
      geographical positions to be converted to RNC (pixel) coordinates and 
      vice-versa.
      3.4.2.17Colour palettes for daytime, nighttime and dusk.
      3.4.2.17.1Colours used for daytime viewing should be those used on the 
      paper versions of the same charts.
      3.4.2.17.2Colours for dusk and nighttime should follow as closely as 
      practicable the Colours and Symbols Standards specified in IHO Special 
      Publication S-52, Appendix 2.
      3.4.2.18Sufficient information which will allow each note, diagram, item 
      of marginalia or other chart subarea of special interest to be found and 
      displayed clearly, simply and quickly even though that subarea may not be 
      located on the portion of the chart currently being displayed.
      3.4.2.19Sufficient information to allow any source diagram, which provides 
      information about data quality, to be displayed clearly, simply and 
      quickly even though the source diagram may not be located on the portion 
      of the chart currently being displayed.
      3.5Updates 
      3.5.1The following meta-data should be included for each RNC update. Where 
      an RNC image file contains one or more discrete chart image, e.g. chart 
      insets, in addition to the main panel of the chart, the meta-data should 
      be sufficient to identify to which the update applies.
      3.5.1.1Producing agency identifier specified using the producing agency 
      codes listed in Annex A to Appendix A of the IHO publication S-57.
      3.5.1.2Update number.
      3.5.1.3Update date.
      3.5.1.4RNC to which the update applies.
      3.5.1.5.1Chart edition date to which the update applies.
      3.5.1.6Any changes to the meta-data of the RNC being updated (e.g. if a 
      chart note changes, the relevant changes in RNC meta-data need to be 
      included in the update).
      3.5.1.7Sufficient information to allow the update to be applied 
      automatically to the RNC and for the update to be displayed.

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ANNEX A
 
RCDS MODE OF OPERATION
(Appendix 7 to the IMO Performance Standards for ECDIS)
      Notes: 1)The RCDS Mode of Operation, adopted by IMO resolution MSC.86 (70) 
      in December 1998, is reproduced in this publication for convenience, with 
      the kind permission of the International Maritime Organization, London.
      Notes: 2)2) This should be read in conjunction with the IMO Performance 
      Standards for ECDIS, which have been reproduced in Annex B to Publication 
      S-52, 5th Edition.

Whenever in this appendix reference is made to provisions of the Annex related 
to ECDIS, ECDIS should be substituted by RCDS, SENC by SRNC and ENC by RNC, as 
appropriate.
All paragraphs of the Annex related to ECDIS are indicated as to whether they 
apply to RCDS, do not apply to RCDS, or are modified in order to apply to RCDS. 
These paragraphs are followed by additional requirements for ECDIS equipment in 
the RCDS mode.
      1.INTRODUCTION
      1.1Paragraph applies to RCDS.
      1.2When operating in the RCDS mode, ECDIS equipment should be used 
      together with an appropriate folio of up-to-date paper charts. 
      1.3 – 1.7Paragraphs apply to RCDS.
      1.8RCDS should provide appropriate alarms or indications with respect to 
      the information displayed or malfunction of the equipment (see Table 1 of 
      this Appendix).
      2.DEFINITIONS
      2.1Raster Chart Display System (RCDS) means a navigation information 
      system displaying RNCs with positional information from navigation sensors 
      to assist the mariner in route planning and route monitoring, and if 
      required, display additional navigation-related information.
      2.2Raster Nautical Chart (RNC) means a facsimile of a paper chart 
      originated by, or distributed on the authority of, a government-authorized 
      hydrographic office. RNC is used in these standards to mean either a 
      single chart or a collection of charts.
      2.3System Raster Nautical Chart Database (SRNC) means a database resulting 
      from the transformation of the RNC by the RCDS to include updates to the 
      RNC by appropriate means.
      2.4 – 2.5Paragraphs do not apply to RCDS.
      2.6Paragraph applies to RCDS.
      3.DISPLAY OF SRNC INFORMATION
      3.1Paragraph applies to RCDS.
      3.2SRNC information available for display during route planning and route 
      monitoring should be subdivided into two categories:
      .1 the RCDS standard display consisting of RNC and its updates, including 
      its scale, the scale at which it is displayed, its horizontal datum, and 
      its units of depths and heights; and
      .2 any other information such as mariner's notes.
      3.3Paragraph applies to RCDS.
      3.4When a RNC is displayed on the RCDS, it should provide an indication 
      advising the mariner if a more detailed (larger scale) RNC is available 
      for the displayed area.
      3.5It should be easy to add to, or remove from, the RCDS display any 
      information additional to the RNC data, such as mariner's notes. It should 
      not be possible to remove any information from the RNC.
      3.6 – 3.7Paragraphs do not apply to RCDS.
      3.8 – 3.10Paragraphs apply to RCDS.
      3.11There should always be an indication if the ECDIS equipment is 
      operating in the RCDS mode.
      4.PROVISION AND UPDATING OF CHART INFORMATION
      4.1The RNC used in RCDS should be the latest edition of that originated 
      by, or distributed on the authority of, a government authorized 
      hydrographic office and conform to IHO standards. RNCs not on WGS-84 or 
      PE-90 should carry meta-data (i.e., additional data) to allow 
      geo-referenced positional data to be displayed in the correct relationship 
      to SRNC data.
      4.2The contents of the SRNC should be adequate and up-to-date for that 
      part of the intended voyage not covered by ENC. 
      4.3 – 4.8All paragraphs apply to RCDS.
      5.SCALE
       This section applies to RCDS.
      6.DISPLAY OF OTHER NAVIGATIONAL INFORMATION
      6.1 – 6.3All paragraphs apply to RCDS.
      7.DISPLAY MODE AND GENERATION OF THE NEIGHBOURING AREA 
      7.1It should always be possible to display the SRNC in "chart-up" 
      orientation. Other orientations are permitted.
      7.2 – 7.4All paragraphs apply to RCDS.
      8.COLOURS AND SYMBOLS
      8.1IHO recommended colours and symbols should be used to represent SRNC 
      information.
      8.2Paragraph applies to RCDS.
      8.3Paragraph does not apply to RCDS.
      8.4Paragraph applies to RCDS.
      9.DISPLAY REQUIREMENTS
      9.1 – 9.2Paragraphs apply to RCDS.
      9.3Paragraph does not apply to RCDS.
      9.4Paragraph applies to RCDS.
      9.5RCDS should be capable of displaying, simply and quickly, chart notes 
      which are not located on the portion of the chart currently being 
      displayed.
      10.ROUTE PLANNING, MONITORING AND VOYAGE RECORDING 
      10.1 – 10.2Paragraphs apply to RCDS.
      10.3Paragraph does not apply to RCDS.
      10.4Route Planning
      10.4.1 – 10.4.3Paragraphs apply to RCDS.
      10.4.4 – 10.4.5Paragraphs do not apply to RCDS.
      10.4.6Paragraph applies to RCDS.
      10.4.7It should be possible for the mariner to enter points, lines and 
      areas which activate an automatic alarm. The display of these features 
      should not degrade the SRNC information and it should be clearly 
      distinguishable from the SRNC information.
      10.5Route monitoring
      10.5.1Paragraph applies to RCDS.
      10.5.2It should be possible to display a sea area that does not have the 
      ship on the display (e.g. for look ahead, route planning), while route 
      monitoring. If this is done on the display used for route monitoring, the 
      automatic route monitoring functions in 10.4.6 and 10.4.7 should be 
      continuous. It should be possible to return to the route monitoring 
      display covering own ship's position immediately by single operator 
action.
      10.5.3 – 10.5.4Paragraphs do not apply to RCDS.
      10.5.5 – 10.5.8Paragraphs apply to RCDS.
      10.5.9The RCDS should only accept data referenced to the WGS-84 or PE-90 
      geodetic datum. RCDS should give an alarm if the positional data is not 
      referenced to one of these datums.
      10.5.10-10.5.13Paragraphs apply to RCDS.
      10.5.14RCDS should allow the user to manually align the SRNC with 
      positional data. This can be necessary, for example, to compensate for 
      local charting errors.
      10.5.15It should be possible to activate an automatic alarm when the ship 
      crosses a point, line, or is within the boundary of a mariner-entered 
      feature within a specified time or distance.
      10.5.6Voyage recording
      10.6.1 - 10.6.4All paragraphs apply to RCDS.
      11.ACCURACY
      11.1 – 11.2All paragraphs apply to RCDS.
      12.CONNECTIONS WITH OTHER EQUIPMENT
      12.1 – 12.2All paragraphs apply to RCDS.
      13.PERFORMANCE TESTS, MALFUNCTION ALARMS AND INDICATIONS
      13.1 – 13.2All paragraphs apply to RCDS.
      14.BACK-UP ARRANGEMENTS
       All paragraphs apply to RCDS.
      15.POWER SUPPLY
      15.1 – 15.2All paragraphs apply to RCDS.



Table 1 
ALARMS AND INDICATIONS IN THE RCDS MODE OF OPERATION
       
      ParaRequirementInformation
       
      10.4.6, 10.5.5AlarmDeviation from route
      10.4.7, 10.5.15AlarmApproach to critical point, line, area or 
      mariner-entered feature
      10.5.7AlarmPosition system failure
      10.5.8AlarmApproach to critical point 
      10.5.9AlarmDifferent geodetic datum
      13.2AlarmMalfunction of RCDS mode

         
         
      3.11IndicationECDIS operating in the raster mode
      3.4, 5.1IndicationInformation under-scale or overscale
      5.2IndicationLarger scale RNC available for the area of the vessel


 
The definitions of indicators and alarms are given in Appendix 5.
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