2.2.1  Depth Related Functionality

S-100 ECDIS allows water levels to be automatically adjusted using an interoperable combination of S-101, S-102 and S-104 data, both for monitoring and planning purposes. This is described fully in Annex D of this document.

4.1.1  Basic product specifications and layers

Navigation displays such as the ECDIS main screen must be able to process and display at least the following data products:

With the exception of the ENC layer, which must be permanently on, the mariner must be able to switch the graphical display of S-111, S-124, S-129 on and off. Graphical display of S-101 is defined in Annex E. Additional requirements for the graphical display of S-111, S-124 and S-129 are contained in 12.2.

4.1.2  Projected Data

ECDIS must support the import of data products using unprojected geographic latitude and longitude values. Additionally, ECDIS must support the import of S-102 and S-104 data products using coordinates which are projected using either UTM or UPS projections. Formulas for conversion of such coordinates back to unprojected latitude and longitude values are contained in Annex H of this document.

4.1.3  Other data products

The intention is that in future editions of this document, when operational product specifications are published by IHO, navigation displays such as the ECDIS main screen will allow the mariner to process the following data products

5.2.1  Pixmaps

Pixmaps can be used for defining pattern fills for areas that are not sufficiently described to be symbolised, or for which no symbol exists in the IHO Geospatial Information (GI) Registry.

5.2.2  Colour coding scheme

The Portrayal Catalogue uses a colour scheme, which classifies colours by their usage. Each colour usage is represented by a colour token. Each colour token corresponds to a colour definition given in CIE and/or sRGB coordinates in one of a set of colours; each set is intended for a different bridge lighting condition. Each such set of colours is referred to as a “palette” and is generally identified by a descriptive name, such as “Day”, “Dusk” and “Night”. A particular colour token is often assigned different CIE/sRGB coordinates in different palettes (especially day/night/dusk palettes).

A “colour profile”, as the term is used in S-100, is a collection of tokens within a single XML file. An ECDIS makes palettes for day, night, and dusk conditions available on the system (MSC 530(106) / A10.4.

Symbols, fill styles and line styles refer to the colour tokens as part of the symbol definition.

5.2.3  Symbols

The Portrayal Catalogue provides a set of symbols. These symbols are encoded as SVG files which conform to the S-100 SVG profile

5.2.4  Area fills

The Portrayal Catalogue offers various ways to fill areas. They can be filled with an opaque colour; with a colour shown with some transparency; or with a pattern of symbols (fill pattern) or with a centred symbol. Fill patterns and centred symbols are a solution for the symbolization of areas in special situations. Fill patterns or centred area symbols may be used to symbolize the case when the entire display window lies within an area (the area boundary is not visible).

Area boundaries should not be visible on the edge of the display window when the display window is enclosed by an area. However, if the boundary is actually on the edge of the display window, it should be visible.

5.2.5  Line styles

The Portrayal Catalogue uses two types of line styles: simple line styles and complex line styles. Simple line styles are solid, dashed or dotted lines with varying colour and thickness (width or stroke width). Complex (or “composite”) line styles are composed of repeating line patterns.

Simple line styles are generally described by continuity, width, and colour. The full specification of a simple line style may also include other elements such as dash interval, cap and join types (see S-100, Clause 9-12.4 and S-100, Clause 9a-11.2.2.3), defaults for which may be set in the Portrayal Catalogue. Complex line styles consist of additional elements, described in S-100, Clause 9-12.4 and S-100, Clause 9a-11.2.2.3.

Complex linestyles may be one-sided (symbols, text, etc., which are part of the line extend to only one side of the line) or two-sided (symbols, text, etc. extend on both sides of the line).

5.2.6  Portrayal of Shared Edges.

Shared edges portrayed with dash patterns may be presented incorrectly to the mariner when the ECDIS draws the edge in both directions. This issue can occur along the shared edges of features which abut, such as restricted areas or anchorages where adjacent edges are drawn in opposite directions.

Rendering the dash pattern in both directions can alter the pattern from what is intended, and in some cases may result in a solid line.

In the figure below, note the edges under the green highlight:

This issue can also affect complex line styles, for example:

5.2.7  Text

S-101 and other Product Specifications may utilize a cartographic feature called TextPlacement that is used in association with a feature to optimise placement of labels (usually, either feature name or light characteristic description string).

There are three types of text instructions possible in portrayal catalogues:

However, explicit cartographic placement along curves or relative to area/local CRS cannot be explicitly encoded in S-101 datasets, though it can be encoded in portrayal rules in a Portrayal Catalogue (S-100, Clause 9a-11.2).

5.2.8  Style sheets

Cascading Style Sheets (CSS) files are used to provide different sets of stroke and fill style instructions to be applied to symbols. This mechanism allows changing colours and line weights used in the symbols by swapping CSS files according to the desired colour scheme.

In principle, any style attribute can be set in a CSS file, but the CSS files in IHO Portrayal Catalogues are restricted by S-100, Clause 9b-4.4 to only two use cases: setting stroke and fill colours, altering the visibility of elements which are not normally displayed (for example, the pivot point).

5.2.9  Display planes

Display planes are used to split the output of the portrayal functions into mutually exclusive lists. An example of this is the separation of chart information drawn under a radar image and chart information drawn over a radar image.

5.2.10  Display (drawing) priorities

Display priorities are also called “drawing priorities” in S-100, Part 9 and S-100, Part 9a.

Display priorities control the order in which the output of the portrayal functions is processed by the rendering engine within a display plane. Priorities with smaller numerical values will be processed first.

The display priority applies irrespective of whether a feature is a point, curve or surface. If the display priority is equal among features, curve features have to be drawn on top of surface features whereas point features are drawn on top of both. If the display priority is still equal among features of the same type of geometry (curve, surface or point) the given sequence in the data structure of the System Database, or some other neutral criterion, should be used for a decision as to which feature is drawn on top.

5.2.11  Viewing groups

The viewing group controls the content of the display. It provides an on/off switch in the Portrayal Catalogue for all drawing instructions assigned to the corresponding viewing group.

5.2.12  Viewing group layers

A viewing group layer defines a collection of viewing groups whose visibility can be simultaneously toggled on/off by an application.

5.2.13  Display modes

A display mode defines a collection of viewing group layers which can be simultaneously toggled on/off by an application.

5.2.14  Rules

A portrayal rule describes the transformation of feature data into drawing instructions.

5.2.15  Context

The context is a set of parameters whose values alter the portrayal processing. These parameters can be used to provide contextual information to the execution of rules in portrayal processing. Examples are settings of depth values for the safety depth, shallow and deep contours.

5.2.16  Validity times

Drawing instructions can be designated as being valid only during a specified interval, which may be open-ended at either beginning or end, or a single time point (with beginning and end the same). Intervals may be specified in terms of date, time (of day), or date-time endpoints.

The start and end instants are defined by their date/time component of the smallest granularity. For example, if the end instant is specified a date without a time of day, and the interval is “right-closed”, the end instant is midnight at the end of the specified day (240000 in ISO 8601 terms). This is consistent with the S-100 treatment of dateStart and dateEnd attributes (see S-100, Clause 3-8-3 (Interpretation of models of time intervals and period), but note that the open/closed nature of the interval affects the interpretation for Part 9 time intervals — if the same interval is specified as “right-open” the start time point is midnight at the beginning of the specified day (000000 in ISO 8601 terms).

7.1.1  Distinguishing between official S-100 data and additional data

IMO Performance Standards (MSC.530(106)/Rev.1, Section 1.5) states that ECDIS should enable the mariner to execute all route planning, route monitoring, and positioning and sections 3.3-3.4 mean that the ENDS and System Database may contain information from nautical publications as well as ENCs. This specification requires that ECDIS must distinguish between official data and such additional data from users (mariners) and manufacturers. The colour and symbol usage for mariners’ and manufacturers’ data in the IHO GI Registry and the Portrayal Catalogues for S-100 data products are designed to implement this while ensuring the display remains clear and uncluttered.

The official status of data delivered to the ECDIS is defined by the value of a role. This is encoded in the ST field of the X.509 certificate referenced in the mandatory digital signature accompanying content in the exchange set catalogue. Digital signatures are mandatory for any data imported into the ECDIS, whether official or not. The mandatory fields within every authenticating certificate are defined as:

For ECDIS, the ST code holding the role determines whether a dataset or supporting resource is non official or official. The following codes are supported by the IHO data protection scheme:

ST field values using the role OTHER_DATA_PRODUCER (or any other value not included in the list above, or those not conforming to the CN MRN format above) represent data or catalogue content which is non official.

7.1.2  Supplemental display items

The following information must be shown on demand

7.1.3  Navigational Warning functions

Specification for the display of navigational warnings are contained in section Clause 10.12

7.1.4  Units

The units of height and depth listed below must be permanently indicated.

Equivalent values using other units may also be shown:

Depth: Metres and decimetres.

Height: Metres.

Additionally, the units listed below must be available, on demand and indicated in the display legend.

Position: Latitude and longitude in degrees, minutes and decimal minutes.

Distance: Nautical miles and decimal miles; or metres.

Speed: Knots and decimal knots.

7.1.5  Legend

A standard legend of general information relating to the area displayed, applicable to the position selected by the mariner, must be shown on a graphic or text display. See Clause 10.11.1 for detail.

7.2.1  Priority layers

The IMO Performance Standard divides System Database information into three categories that determine what data is to be on the display: Display Base (always present on the display); Standard Display (the default display); and all other information (displayed on demand). (MSC.530(106)/Rev.1, Appendix 2).

There are 9 basic priority layers for the drawing sequence of the data on the display, ordered from higher to lower priorities in the list below:

This list is not intended to indicate a drawing sequence, but to specify that the information content of category n+1 must not obscure the information content of category n, or any higher-priority category (n-1 etc.).

7.2.2  Radar priority

Radar priority for a given display plane is described by the order attribute within the Portrayal Catalogue.

The RadarOverlay Portrayal Catalogue context parameters must be updated whenever the radar image is toggled on or off.

When present, the radar image should be written over Portrayal Catalogue display planes with a negative order attribute; and below display planes with a positive order attribute.

In order to meet the requirements of MSC.530(106)/Rev.1, Section 11.4.18 to adjust the ship’s position, the ECDIS may incorporate the capability of temporarily changing the radar image priority during the adjustment.

8.2.1  Introduction

In a navigation system the viewing distance will be about 70 cm for route planning, but experience to date indicates that the viewing distance for important features during route monitoring may be several metres.

Human factors experts recommend that symbols and characters subtend 20 arc minutes at the observer’s eye. (For example, a symbol viewed from 70 cm for route planning should be about 4mm in size, 1.5 times the size of a normal chart symbol. Two times chart size is a good general rule.) Symbols and characters important for route monitoring may have to be significantly bigger.

For clear representation, symbols require a minimum number of screen units (pixels), depending on their complexity. A simple chart symbol of height 4mm should extend at least 13 pixels for a screen that just meets the current minimum standards for chart display size and resolution.

The minimum resolution is defined by IEC 61174 and/or IEC 62288.

8.2.2  Minimum Requirement for size and resolution

The minimum sizes for all symbols must be as defined in the Portrayal Catalogue.

Enough “picture units” (pixels) must be used to draw small features and symbols clearly and allow viewers to distinguish similar symbols. Symbols must therefore always be drawn with at least the same number of pixels as are required to draw the symbol at the size defined in the Portrayal Catalogue for the minimum resolution and minimum chart display area.

The CHKSYM01 symbol may be used for comparison; this symbol must measure $5\mathrm{mm}\times 5\mathrm{mm}$ when displayed at its nominal size (that is, scaled to 100%), within the tolerance specified by the IEC testing standard (recommended tolerance: 1 physical pixel width in each of the X and Y dimensions).

Since the CHKSYM01 symbol is quite small for the purpose of on-site system configuration by ordinary users, manufacturers may use an enlarged version or an equivalent method for that purpose.

8.2.3  Zooming

When the display scale is enlarged by zooming in, it must be possible to hold symbol size constant. The same applies to text. Symbol and text size must never be decreased when zooming out.

10.1.1  ENC scale

The term “scale” is used to describe either:

The S-101 ENC values used for the Data Scale attributes minimumDisplayScale and optimumDisplayScale are fixed, and taken from the table below:

Table — minimumDisplayScale and optimumDisplayScale values

The ordering and selection of Data Coverage features by Data Scale, prior to S-101 portrayal is defined fully in Annex E — Dataset Loading and Display (Rendering) Algorithms.

10.3.1  Chart Scale boundary

Where the optimumDisplayScale of the ENC data available changes the ECDIS should warn the mariner of upcoming ENC scale change. Only the major changes in optimumDisplayScale resulting from the scale jumping more than three steps in optimumDisplayScale should be shown. The steps are the defined scale bands in the display Loading and rendering Table E-1.

The “chart scale boundaries”, where the optimumDisplayScale of the data changes by more than three steps, must be symbolised on the ECDIS display by a solid 0.32mm wide line using colour token CHGRD. Alternatively, linestyle SCLBDY51 may be used. The display priority is 9; over-radar; standard display; viewing group 21030.

When scale boundaries of smaller scale Data Coverage areas overlap larger scale Data Coverage areas, that portion of the scale boundary which intersects the larger scale Data Coverage area should not be visible.

10.3.2  Overscale Pattern

ECDIS displays all chart data at the same (mariner selected) viewing scale. In order to avoid leaving parts of the display blank, the display may be rendered using data from multiple datasets using the algorithm defined in Annex E — Dataset Loading and Display (Rendering) Algorithms. These datasets may contain Data Coverage areas with different *optimumDisplayScale*.

The area fill OVERSC01 must be used to indicate Data Coverage areas displayed larger than the maximumDisplayScale, when the area has been selected for display by the ECDIS in order to avoid leaving that portion of the display blank. These Data Coverage areas are those selected after stage 3.b is reached in the SelectDataCoverages function in Annex E — Dataset Loading and Display (Rendering) Algorithms.

For example, an overscale situation arises when the ship approaches a scale boundary from a larger to a smaller scale ENC, typically when leaving harbour. In combining data from the large scale and the small scale ENCs to generate a display at the larger scale, the ECDIS will have “grossly enlarged” the small scale data.

In addition to drawing the scale boundaries, the “grossly overscale” part of the display must be identified with area fill OVERSC01, as illustrated in Figure 11-1.

Figure 11-1 — Illustration of overscale display

In this context, “grossly enlarged” and “grossly overscale” should be taken to mean that the display scale is enlarged/overscale with respect to the maximumDisplayScale. For example, at the left edge of the display scale of 1/12,500 is larger than the maximumDisplayScale of 1/50,000, and so the overscale pattern is required.

Note that in this situation the OVERSC01 area fill should only be shown on the area compiled from the smaller scale ENC. If the area from the larger scale ENC is also overscale, this should be indicated only by the “overscale indication”. The OVERSC01 area fill should not be shown on the part of the display taken from the larger scale ENC

For example if the display scale (MSVS) 1:3,500 is selected, the area of optimumDisplayScale 1:12,500 would have an overscale indication of X 3.6 but would have no OVERSC01 area fill.

10.3.3  Larger scale data available

As the mariner’s display window moves and begins to cover an ENC that is of a larger optimumDisplayScale, the ECDIS must indicate when the ship’s position enters the larger scale ENC, as required by MSC.530(106)/Rev.1, Section 6.1.2.

10.4.1  Graphical indexes of ENCs

The system must be capable of displaying a graphical index of ENCs.

All datasets installed on the system must be included in the graphical index.

Additionally:

The description of dataset extents in S-101 ENC discovery metadata in exchange catalogue files uses a fixed format, described in Annex F.

It must be possible to individually select the display of the graphical index entries for the installed S-57 and S-101 ENCs. The display of each data product must be differentiated.

10.4.2  Graphical indexes of other S-100 products

The ECDIS must additionally implement a capability for displaying graphical indexes of S-102 and S-104 data products, and may implement a graphical index of other non-ENC data products

If the system displays graphical indexes for different products simultaneously it must be possible to individually select the display of each supported data product. The display of each supported data product shall be differentiated.

10.5.1  ENC No data areas

The ECDIS must fill any areas in which there is no installed ENC coverage using area pattern NODATA03, using colour token NODTA. These areas are defined as no data areas.

The indication “No ENC Available” must be shown if the display includes areas in which there are waters with no ENCs installed.

An indication that the mariner must refer to the official chart must also be given whenever line style NONHODAT appears on the display, or whenever the display is comprised of other than ENC data as specified by Clause 7.1.1.

10.5.2  Limit of official S-101 data and non official S-101 data

The limit of official S-101 data on the graphical index defines the limit of official ENC coverage. The definition of official data as opposed to non official data is contained in Clause 7.1.1.

The appearance of the “No data” colour (colour token NODTA) and NODATA03 area fill (see Clause 10.5.1) will indicate the end of official data.

If non-official chart data is shown on the ECDIS display, its boundary must be demarcated by the line style NONHODAT. Note that the NONHODAT line style is a “one-sided” line and the boundary of the non official data must be drawn according to S-101 rules to ensure that the diagonal stroke of the line is on the non official data side of the line. The non official data boundary indicated by the NONHODAT line style serves to separate official ENC data from non official chart information.

10.5.3  Limits of other S-100 product data

For all other supported data products, it must be possible for the mariner to be able to individually select for display the “no data” areas and “non official data” boundaries. The display for each supported data product must be differentiated.

For gridded data, the no-data area limits do not need to demarcate areas within the grid extent which are covered by fill values.

10.6.1  Safety Contour

The own-ship safety contour is double-coded by a thick line and a prominent change in depth shade.

If the safety contour selected by the mariner is not available in the System Database, the ECDIS must default to next deeper contour and inform the mariner. If the ship moves onto a new chart, and the safety contour previously in use is no longer available, the ECDIS must again select the next deeper contour, and inform the mariner.

If the mariner does not select a safety contour, the value must default to 30 metres.

10.7.1  Display of date-dependent features by mariner-selected date

To provide the Mariner with effective route planning capabilities and for the look-ahead function during route monitoring ECDIS must display date dependent chart data based on a Mariner selected date or date range (start viewing date and end viewing date).

During route planning and monitoring the Mariner must be able to select a date or date range to display all date dependent chart features.

In this case the ECDIS must be capable of providing the Mariner the ability to set the date the vessel will be in the area (e.g. 02.01.2013 in the above example) and the system should show the new traffic scheme.

10.7.2  Indication of date adjustment

When viewing date or date range do not include the current date, the mariner must be informed by a permanent indication on the chart display that the date has been adjusted. The indication must begin with the text “Display Not Real Time” and the selected date or date range must be readily available.

The use of one of the following formats is recommended:

10.9.1  Scale bar and latitude scale

The IMO Performance Standards require an indication of scale and range as part of the Display Base. The display scale determines which must be used:

The scale bar or latitude scale must always be drawn vertically at the left side of the chart display, just clear of the border of the display. The symbols and drawing parameters are described in Table 11-1.

The placement must be 3mm in from the border of the display. The symbol must be properly sized to represent 1 nautical mile at the scale of the display (for Case 1) or 10 nautical miles at the scale of the display (for Case 2).

Table 11-1 — Scale bar presentation parameters

IEC define a requirement for indicating the location at which the scale is calculated under certain circumstances.

10.9.2  North arrow

A north arrow must be provided as part of the Display Base according to the IMO Performance Standard. The north arrow must always be shown at the top left corner of the chart display, just clear of the scale bar or latitude scale. Other requirements for the north arrow are defined in IEC 61174.

The symbol ‘NORTHAR1’ must be used to indicate true north. It must be placed in the top left corner of the chart display, on the inner side of the scalebar. It must be rotated to true north if the display is other than north up, and clear of the scalebar even if the latter extends the full height of the display.

Table 11-2 — North Arrow presentation parameters

10.9.3  Graticule

If the ECDIS shows a graticule (listed in “other information” in IMO Performance Standards (MSC.530(106)/Rev.1) the lines must use the colour token CHBLK.

10.9.4  Display mode

The ECDIS manufacturer must provide the indication of display mode required in the display base by IMO Performance Standards (MSC.530(106)/Rev.1, Appendix 2).

10.9.5  Black level adjustment symbol

Unless the brightness and contrast controls of the monitor are properly adjusted there is a danger that information may be lost from the chart display, particularly at night. Symbol BLKADJ is provided for checking correct adjustment and for re-adjusting as necessary. The BLKADJ symbol is provided as a part of ECDIS Chart 1, see Clause 17.5

10.9.6  Detection and notification of navigational hazards

The IMO Performance Standard for MSC.530(106)/Rev.1, Clause 11.3.7 Route planning states:

MSC.530(106)/Rev.1, Clause 11.4.6 Route monitoring states:

MSC.530(106)/Rev.1, Clause 11.4.8 Route Monitoring states:

The ECDIS must implement support for the Alert and Indications Catalogue which may be provided within each product’s Portrayal Catalogue.

The safety contour value is set by the user; in the absence of a user setting, its default value must be 30m.

The highlight must indicate the intersection between the ship’s look-ahead buffer (computed using speed, course, look-ahead time and cross-track deviation) and the spatial components associated with alert instructions output by the portrayal.

Figure 11-2 depicts indication highlights for points, curves, and surfaces.

Figure 11-2 — Examples of indication highlights

10.9.7  Detection of areas for which special conditions exist

The IMO Performance Standard for MSC.530(106)/Rev.1, Clause 11.3.7 (which applies to Route Planning) states:

MSC.530(106)/Rev.1, Clause 11.4.4 Route Monitoring states;

The ECDIS must implement support for Alert and Indications Catalogues.

10.9.8  Definition of safety contour

The safety contour is defined as the boundary between safe and unsafe areas of the display.

10.9.9  Detection of safety contour

The IMO Performance Standard for MSC.530(106)/Rev.1, Clause 11.3.6 Route Planning states;

MSC.530(106)/Rev.1, Clause 11.4.3 Route Monitoring states;

MSC.530(106)/Rev.1, Clause 11.4.7 Route Monitoring states:

The ECDIS must implement support for Alert and Indications Catalogues

The point, curve or surface must be graphically indicated using the presentation named as “DNGHLT” in the S-101 Portrayal Catalogue, as depicted in Figure 11-3.

Figure 11-3 — Examples of danger highlights in ECDIS

10.9.10  Indications related to ENC accuracy

The IMO Performance Standard for MSC.530(106)/Rev.1, Clause 11.3.6 Route Planning states;

MSC.530(106)/Rev.1, Clause 11.4.9 Route Monitoring states;

When the Mariner has chosen to take accuracy of hydrographic information into account the ECDIS must use a zoneOfConfidence attribute to extend the check area in a horizontal direction for route plans (closer than a user-specified distance) and for own ship (within a specified time or distance set by the mariner, own ship will pass closer than a user-selected distance).

10.9.11  Check area extension value — S-101 only

When the ECDIS is using S-101 without any S-102 depth substitution or S-104 depth adjustment the S-101 QualityOfBathymetricData feature contains a zoneOfConfidence complex attribute. This provides either a horizontalPositionUncertainty sub-attribute If no horizontalPositionUncertainty value is available then the amount of extension must be taken from the sub-attribute categoryOfZoneOfConfidence according to the following table of default values:

Table 11-3 — categoryOfZoneOfConfidence and Accuracy values.

10.9.12  Check area extension value — S-102 depth substitution

When the depth information in the S-101 is substituted by S-102 the zoneOfConfidence.horizontalPositionUncertainty.uncertaintyFixedin the QualityOfBathymetryCoverage feature attribute table (S-100, Clause 10c-9.6.2) from the S-102 must be used instead of the S-101 feature information as defined in the last clause if it is set. If this value is not available then the S-101 value defined in the previous clause must be used instead.

10.9.13  Check area extension value — S-102 depth substitution and S-104 adjustment

When the depth values in the S-101 are substituted for S-102 and also adjusted by the S-104 values (as documented in Annex D) then the total value for the extension of the check area, as defined in the previous clause must then be further adjusted by adding the uncertainty value in the S-104 feature attribute table zoneOfConfidence.horizontalPositionUncertainty.uncertaintyFixed if defined.

For example, when the ECDIS is using S-101 only, if the value of “closer than user specified distance is 100 m and if the value of categoryOfZoneOfConfidence is A2 (a value of 20 m from the table of defaults) then the check is extended in the horizontal direction up to 120 m.

Figure 11-4 — Example Danger Highlight extended by underlaying value of categoryOfZoneOfConfidence, left is without extension and right is with extension

For the S-101 case, when multiple QualityOfBathymetricData features with different categoryOfZoneOfConfidence values underlay the check area, then the value of extension changes at the point where the original non-extended check area crosses the boundary of the QualityOfBathymetricData areas with different categoryOfZoneOfConfidence values, see the example below:

Figure 11-5 — Example Extension of check-area by multiple underlaying QualityOfBathymetricData areas with different values of categoryOfZoneOfConfidence

10.9.14  Enhanced Safety Contour and Water Level Adjustment.

The term “Enhanced Safety Contour” means a safety contour created from bathymetric grid data using the value set by the user. With ENCs the user sets a value for the safety contour, but if a contour of that value is not found in the ENC then the safety contour defaults to the next deepest available contour which can be substantially deeper than the value requested by the user.

Bathymetric grid data allows the user the ability to define a value and for the system to delineate areas of safe and unsafe water based on that value. The areas defined can then be used for the definition of safety contour and attendant alerts/indications. When this is done contextual ENC features with depth information are also substituted from the bathymetric grid to present the user a harmonised picture.

The combination of S-101 with S-102 and S-104 together enable Water Level Adjustment (WLA), allowing the water level data contained in S-104 to complement the S-102 and S-101 chart data. As with depth information, WLA processes adjust attribute values in the ENC data to present the user with a harmonised picture.

Annex D defines the detailed mechanisms for Enhanced Safety Contour and Water Level Adjustment. The ECDIS must support the Enhanced Safety Contour and Water Level Adjustment features.

10.10.1  Legend

A standard legend of general information relating to the area displayed, applicable to the position selected by the mariner, must be shown on a graphic or text display. This legend must contain at minimum (and, as applicable):

Since attempting to display all the above items for all displayed data products may lead to an unduly large legend, manufacturers may suppress information from data products other than ENCs. If this is done, the suppressed information should be available through simple operator action, such as a temporary expansion of the legend activated by clicking on a target in the legend. (Note that some of the items will be the same for all data products — in particular, units and datums should be the same for all products, or converted to present the same display result, in order to reduce the chances of user error.)

10.10.2  Legend details

The legend must additionally indicate the vertical datum of any S-102 and S-104 used for Enhanced Safety Contour and Water Level Adjustment on the display. If the vertical datums are the same then a single indication is enough to cover S-101, S-102 and S-104.

10.10.3  ECDIS Legend

The ECDIS chart legend containing the items in Table 11-4 must be available for display for a position selected by the Mariner.

Table 11-4 — Legend elements

The list above is the minimum that must be available, but the complete list need not always be shown. Individual items may be picked by the mariner for display for a period; examples are magnetic variation, data quality for depths, etc.

10.11.1  Manual updates

It must be possible to make the following manual updates to an ENC:

A manually updated feature must be capable of the same performance in feature selection, response to cursor-picking, etc, as an ENC feature. In addition, it must provide updating information (identification and source of update, when and by whom entered, etc) on cursor picking

Manual chart updates, which are subject to human error, must be distinguished from official information and updates applied automatically. Additionally:

10.11.2  Additional Mariner’s Information

Mariner’s Caution Notes and a Mariner’s Information Notes must be presented according to IEC 61174 or IEC 62288, as applicable [and available].

Point cautions and notes entered by the mariner and the manufacturer must be distinguished by the colours orange and yellow respectively.

10.11.3  Automatic Updates

Only ISO 8211 and GML encoded data can support updates, as described in S-100, Part 10a and S-100, Part 10b respectively. The use of GML updates as described in S-100, Part 10b is used, in particular, by S-128 to update catalogue information used by the ECDIS to produce update Status Reports, as described in Annex C — ECDIS Update Status Reports.

10.11.4  Identifying automatic chart corrections on demand

On Mariner demand automatic chart corrections of ENC information must be highlighted as described in the following sub-clauses.

10.11.5  Update Information

The S-101 Feature Catalogue also provides encoders with an Update Information feature that is used to represent a change to the information shown.

The intention of the Update Information feature is to show the extent of changes contained in either updates or new editions of S-101 datasets. This is separate to the highlighting mechanism described in the previous clause and is optionally included by data producers in ENCs.

For example, when an ENC update contains updates to various features that adjoin a feature that was actually update, the producer will use an Update Information feature to indicate the actual feature that was affected and a brief description of the changes.

The ‘Update Review’ IMS must be implemented to allow update information features to be portrayed and reviewed on demand.

10.11.6  Non-official (Non-ENC) Chart Information

Non-official data added to existing official ENC data to augment the chart information must be distinguished from the official information as follows:

Point feature: Superimpose symbol CHCRID01.

Curve feature: Overwrite with line style CHCRID01.

Surface feature: Overwrite area boundary with line style CHCRID01 and superimpose symbol CHCRID01 on any centred symbol.

Non-official data must be distinguished from manually updated chart information, which uses the same identifiers, by cursor picking.

Non-official chart information may be updated by any systematic procedure. A record of updates must be maintained.

The mariner must be able to remove all non-official chart information if the need should arise.

10.12.1  Additional Portrayal requirements of the Graphical User Interface

A dedicated interface must be provided to allow users to interact with NAVWARN messages. This interface must, at a minimum, provide the following functionality;

10.12.2  Filtering Navigational Warning information

The mariner must be able to select the graphical display of S-124 navigational warning (NAVWARN) dataset on or off.

To ensure only relevant information is displayed, and to ensure an uncluttered screen, the mariner must be able to filter the NAVWARNs as follows :

At a minimum, filtering functionality must be included that allows the user to classify the relevance of a NAVWARN against the intended route as:

On chart should be the default classification for all NAVWARNs.

Additional filtering functions may include options such as;

These filters may then be used to assist the navigator in classifying a NAVWARN according to its relevance for the route.

10.12.3  Cancelled datasets

When a S-124 dataset is cancelled it must not be displayed on the navigation screen, but must be available for review in the on demand listing of NAVWARNs in the navigation system and marked as cancelled.

10.12.4  Portrayal of feature types

The NAVWARNAreaAffected class does not have a portrayal defined to avoid causing significant cluttering on the navigation screen. Rather, the feature must be highlighted by the system if selected from a pick report or by other means for interrogation by user.

When a NAVWARNPart is not portrayed, such as when user selections mark it not to be visualized, any associated TextPlacement features must also not be portrayed.

13.3.1  Sorting order of results

The Pick Report must be organized to facilitate navigation through complex reports in a manner logically consistent with the layering presented on the screen.

The order of features must correspond to the drawing order. Features must be prioritized using the highest priority active drawing instruction associated with the feature. Only active drawing instructions which intersect the pick area should be evaluated during sorting.

13.3.2  Hover-over function

The ECDIS may provide a hover-over function for Mariners to access important charted feature details without having to select a Pick Report. If this function is implemented within an ECDIS, the Mariner must be able to turn hover-over functionality on and off.

17.3.1  General

The ECDIS manufacturer can use any technology to build the display as long as their display fulfils the requirements of this specification.

17.3.2  Display calibration and verification

The ECDIS display must be calibrated initially in order to transform the CIE colour table coordinates to screen coordinates. The main components of the ECDIS display are the monitor and the image generator. Both the monitor and the image generator used to drive the ECDIS display can be calibrated together as a colour generating unit. Another alternative is to calibrate separately both the monitor and image generator.

The following international standards describe methods for calibration of a monitor’s RGB values to produce an output. Other methodologies may be followed, but the same verification test requirements apply regardless of method.

CIE 122-1996 Technical Report: The Relationship between Digital and Colorimetric Data for Computer-Controlled CRT Displays.

IEC 61966-3:2000 Multimedia systems and equipment -Colour measurement and management — Part 3: Equipment using cathode ray tubes, Edition 1.

IEC 61966-4:2000 Multimedia systems and equipment-Colour measurement and management — Part 4: Equipment using liquid crystal display panels, Edition 1.

The ECDIS display calibration must be verified for type approval of all monitors.

17.3.3  Colour control, contrast and brightness controls

There are a variety of technologies available for monitors to be used for ECDIS display. Different technologies have different methods to control colour, contrast and brightness, but some basic rules apply for all of them.

17.3.4  Effect of controls

The contrast control of a display generally shortens or extends the range of luminance available, making the display appear darker or brighter.

On the other hand, the brightness control shortens or extends the range of colour saturation available by adding white (which extends the range by making colours other than black less saturated), or subtracting white (colours become darker, more saturated.)

To the viewer, it has much the same apparent effect as contrast, but it achieves this by altering the colour contrast of the colour tables between foreground and background colours, and this may result in some features becoming harder to see, particularly at night. More importantly, making the night display more saturated may drop some dark colours below the cut-off point, into black, thus losing distinctions such as shallow versus deep water.

17.3.5  Use of the controls

Colour tables are provided for day, dusk and night. The mariner must be provided with the control to make fine adjustments between these tables; the calibration position must be marked as a reference for this.

The general principle is that all colour calibration controls must have a provision to return to the calibrated settings.

The ECDIS manual must carry a warning that use of the ECDIS with uncalibrated settings may adversely affect the visibility of information on the display.

17.3.6  Setting the controls for route monitoring

The ECDIS display carries far more detail than a radar display, and requires correspondingly more attention to the correct selection of colour table and the correct adjustment of the controls.

This particularly affects the black-background displays, and is critically important at night, because all colours of the night table, particularly those for large areas, have to be set very dark to avoid loss of night vision, and if the control is turned down too far these colours will disappear into the black background. As a result, chart information will be lost.

The situation will be worse if one of the day tables is improperly dimmed for use at night, instead of switching to the night table.

It is important that the display be adapted to lighting conditions on the bridge by selecting the correct colour table: “Day” for bright sunlight; “Day” or “Dusk” for general daylight viewing; “Dusk” for twilight; and “Night” for the night-darkened bridge.

The controls should only be used for fine adjustment within the appropriate colour table.

To ensure that the controls are always set to a level above that at which information will be lost, the black-adjust symbol BLKADJ must be available to the Mariner, treated as “Standard display”, to be called up at any convenient point on the screen. The instructions for its use by the Mariner must be incorporated in the ECDIS manual.

The following text box contains an example of instruction for an LCD type of Monitor. The LCD type of monitor used in this example has only one mariner control, called “brilliance”. Internally the monitor has also other controls available for service engineers. These internal controls include also controls named as contrast and brightness.

17.4.1  Colour conversion tolerances and tests

17.6.1  Specification for ECDIS Chart 1 and the Colour Test Diagram

17.6.2  The Colour Test Diagram

A multi-purpose colour differentiation test diagram is illustrated in Figure 18-1. This consists of 20 squares each coloured with one of the 4 main background colour fills (such as shallow water blue); and each having a diagonal line in one of the six important foreground colours (such as mariner’s orange). Each diagonal line is $0.64\mathrm{mm}$.

The diagram is in the form of a dataset and so can be displayed using any of the three colour palettes. This diagram is intended:

Both the Colour Test Diagram and the instructions for its use are included within the IHO S-164 test datasets Chart 1 exchange set, and must be made available to the Mariner. In addition, a grey scale is included in Clause 17.6 for use by maintenance technicians in checking colour tracking in an ageing display.

The Colour Differentiation Test diagram is not needed during route monitoring.

Note that the Colour Differentiation Test Diagram will not be true to colour unless it is projected on a calibrated screen and is generated using the digital format provided by IHO, which correctly reproduces the colour tokens of the Presentation Library.

The colour differentiation diagram is required in “Day” and “Dusk” colours so that the Mariner can verify that the ECDIS display monitor has the colour differentiation capability needed to distinguish between the various colour-coded areas, lines and point symbols of the ECDIS display.

NOTE  For illustrative purposes only. Actual ECDIS Chart 1 datasets must be used

Figure 18-1 — Colour differentiation diagram - Day

Providing the diagram

The Colour Differentiation Test diagram must be provided to enable the Mariner to verify that the display screen still retains the colour differentiation capability needed to distinguish between the various colour-coded areas, lines and point symbols of the ECDIS display.

The diagram will not be true to colour unless it is displayed on a calibrated monitor and is generated using the provided ENC portrayal catalogue.

To provide the diagram the dataset labelled “10100AACH1WOO” must be used. This dataset must be initially displayed at the optimumDisplayScale so that the extent of the imaginary chart data covers the entire ECDIS display.

The diagram consists of twenty numbered squares extending over the whole of a $270\times 270\mathrm{mm}$ screen Each square is coloured with one of the four main background area shades (such as shallow water blue, DEPVS), and each carries a two-pixel wide diagonal line in one of the important line or symbol foreground colours. These are arranged as follows:

Four main background colours:

Six important foreground colours:

The procedures for carrying out the test are documented in S-164.

17.6.3  Relationship to S-57 Chart 1

The Chart 1 datasets are located alongside the existing S-57 Chart 1 cells to allow use of both in Dual Fuel mode.

17.6.4  The Black-adjust symbol

The black-adjust symbol BLKADJ01 is to allow the Mariner to adjust the display for ambient illumination on the bridge of a ship. An ECDIS must have the black-adjust symbol displayed whenever the mariner is adjusting the display (that is, depending on the technology of the display brilliance, brightness, contrast, etc), as required by Clause 17.3.1.

18.3.1  Overlaps and gaps in ENC coverage

There may be cases where ENCs in the same scale range overlap. Such may be the case at agreed adjoining producer data limits, where, if it is difficult to achieve a perfect join, an overlapping buffer zone of up to 5 metres may be used.

Where an overlap of more than 5 metres between two or more datasets exists the ECDIS must only display one dataset for the overlap area and provide a permanent indication “overlap”.

18.3.2  Overlaps and gaps between other data products

Overlaps in datasets of the same scale range in products other than the ENC must be indicated by an on-demand indication “Overlap in ??? data” (where ??? is the abbreviation for the data product).

An exception to this rule is S-102 and S-104 data used for Water Level Adjustment. In these cases the ECDIS must only select and use a single dataset from the overlapping data available and provide a permanent indication “overlap” as per ENCs.

Coverage gaps in products other than the ENC can be expected and should not be indicated.

Similarly, overlaps between different data producers’ ENC and other data products other than ENC should also be expected. Certain features, such as navigational warnings, can extend far beyond national boundaries and may therefore overlap other data producers’ ENC data. An indication is not needed in these cases.

18.4.1  Introduction

The current Editions of S-65, S-57 and S-63 continue to apply to the production and data delivery for S-57 ENC updates. S-52, Appendix I continues to apply to the processing of S-57 updates on ECDIS.

18.4.2  General requirements

18.4.3  Automatic Update