NAV 44/7/8
Appendix E
DRAFT RECOMMENDATION FOR A
RASTER NAVIGATIONAL CHART (RNC) PRODUCT SPECIFICATION
1 INTRODUCTION
1.1 The elements of this product
specification define The minimum requirements a Raster
Nautical Chart (RNC) must have to satisfy the draft
performance standard for a Raster Chart Display System
(RCDS).
1.2 This product specification does
not define underlying raster data structures of a raster
nautical chart. The national hydrographic office producing
the raster nautical chart should select that data structure.
2 DEFINITIONS
2.1 For the purpose of this product
specification:
2.1.1 Raster 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.
2.1.2 Raster Nautical Chart (RNC) means
a digital facsimile of a paper chart originated 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.
2.1.3 Notice to Mariners (NM) means a
published change to an RNC originated by or distributed under
the authority of a government authorized hydrographic office.
3 RNC REQUIREMENTS
3.1 An RNC should contain an image
file which is a digital facsimile of an existing, official
paper chart, and it should also contain meta data describing
the RNC as stated in this product specification.
3.2 The 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.
3.3 Image Files
3.3.1 The digital format of the image
file should be determined by the national hydrographic office
originating the RNC.
3.3.2 The resolution of the digital
image (pixels-per-inch)and any method used to compress that
image file should be sufficient to display clearly all
information that was contained on the original paper nautical
chart.
3.3.3 The 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 metadata, should allow a
ship's position to be displayed at least as accurately as
when using the original paper chart.
3.4 Meta Data
3.4.1 The digital format of the meta
data sbould be determined by the national hydrographic office
originating the RNC.
3.4.2 The 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;
3.4.2.1 Producing agency identifier
specified using the producing agency codes listed in Annex A
to Appendix A of IHO publication S-57;
3.4.2.2 RNC number;
3.4.2.3 Chart identifier (e.g. chart number)
if different from the RNC;
3.4.2.4 RNC edition date;
3.4.2.5 Chart edition date and/or chart
edition number;
3.4.2.6 Last update or Notice to Mariners
applied;
3.4.2.7 Previous updates or Notice to
Mariners applied;
3.4.2.8 Chart scale;
3.4.2.9 Orientation of north;
3.4.7.10 Projection and associated
projection parameters;
3.4.2.11 Horizontal datum;
3.4.2.12 Horizontal datum shift to WGS84 if
the chart datum is not WGS84;
3.4.2.13 Vertical datum;
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