Presentation library
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- 9.2.1 SHOWPOINT Example
- 9.4.1 SHOWAREA Examples
- 10.1.2 Unknown or Missing Mandatory Attributes
- 10.1.5 No Data Coverage
9.2 SHOWPOINTName: SY – Showpoint, Show symbol command. Syntax: SY(SYMBOL [, ROT]); Description: The SY command displays a symbol at a given point on the display. The command takes a standard symbol name as its first mandatory argument. A second parameter can impose a rotation on the symbol about the pivot point. In the case of an area object the “SY” command is used to display a centred area symbol. Parameters: SYMBOL: The name of the symbol to be displayed, e.g. ISODGR01. This will be the name as defined in the vector description language SYNM field. ROT: An optional rotation parameter. The following notes apply to this parameter. Symbols with no rotation shall always be drawn upright with respect to the screen. Symbols with a rotation instruction shall be rotated with respect to the top of the screen (-y axis in figure 2 of section 8.1). Symbols rotated by means of the six-character code of an S-57 attribute such as ORIENT shall be rotated with respect to true north. The symbol shall always be rotated about its pivot point. Rotation angle is in degrees clockwise from 0 to 360. The default value is 0 degrees." 9.2.1 SHOWPOINT ExampleSY(BOYCAR01);SY(LIGHTDEF,135) :
SY(EBBSTR01,ORIENT)
9.3 SHOWLINEName: LS – Showline (complex linestyle) or LC – Showline (simple linestyle).
LS( PSTYLE, WIDTH, COLOUR); LC(LINNAM);
The SHOWLINE instruction is designed to symbolize line objects. It is also used within the SHOWAREA instruction to symbolize area boundaries. The command is used to show simple or complex line-styles (described below) and subsequent commands may add a symbol or text as well. Parameters: PSTYLE: Predefined line style parameter: One of three values: 'SOLD' (_________) 'DASH' (‑‑‑‑‑) dash: 3.6 mm; space: 1.8 mm 'DOTT' (.........) dot: 0.6 mm; space: 1.2 mm WIDTH Line width parameter. Units are 0.32 mm (approximately pixel diameter) COLOUR Line colour parameter. A valid colour token as described in section 7 LINNAM: Name of complex linestyle. This parameter will symbolise the line using the complex linestyle named by the LINNAM parameter. 9.3.1 SHOWLINE ExampleLS(DASH,2,CHMGD). Displays a dashed line in "chart magenta, dominant", 0.6 mm (2 x 0.3 mm) width. LC(ACHARE51). Displays the complex line‑style called ACHARE51 defined for borders of anchorage areas. (see below). 
9.4 SHOWAREAName: AP – Showarea (area fill) or AC – Showarea (pattern fill).
AP(PATTERN) AC(COLOUR [,TRANSP] )
The two showarea commands are used for symbolising area objects (often in conjunction with linestlyes for border rendering). There are two types of colour fill: area fill with a basic colour using one of the standard colour tokens. pattern fill using a pattern to fill areas. Parameters: COLOUR: colour fill parameter. A valid colour token as described in section 7 PATTERN: the name of the pattern TRANSP: Transparency, an optional parameter for colour fills used to make a fill partially transparent. If the transparency parameter is not set then the default value is 0%, i.e. an opaque colour fill. There are three permissible values: 25% where 3 out of every 4 pixels use TRNSP 50% where 2 out of every 4 pixels use TRNSP 75% where 3 out of every 4 pixels use TRNSP 9.4.1 SHOWAREA Examples
9.5 CALLSYMPROCName: CS – CALLSYMPROC: Call conditional symbology procedure. Syntax: CS(PROCNAME); Description: The CALLSSYMPROC command “CS” calls a named conditional symbology procedure. It is used either on its own in order to symbolise a particular class of object/attribute combinations or in conjunction with other commands in order to add symbols to the display dependent on ECDIS Mariner settings, e.g. The lookup for ACHARE is “SY(ACHARE51);LS(DASH,2,CHMGF);CS(RESTRN01)” Note that the calling of the conditional symbology may affect values in the rest of the lookup table entry, for instance the viewing group or display priority may be affected by the operation of the conditional symbology procedure invoked by the SY command. Parameters: PROCNAME: The name of the conditional symbology procedure to invoke, e.g. RESTRN01 in the above example. Conditional symbology procedures are normally named by the object class that is interpreted by the procedure. The name is normally an 8 letter code that is composed of the class code (6 letters) and a serial number (2 letters). ECDIS RequirementsThis section provides ECDIS developers with other details of ECDIS display that shall be taken into account while designing ECDIS. 10.1 Data ConsistencyENC presentation depends very much on the consistency of the underlying S-57 data. Thus ECDIS manufacturers should be aware of the consistency of the data that will be processed by their ECDIS. 10.1.1 Unknown ObjectsFeature objects shall be of an officially adopted object class. If feature objects are of proprietary non-ENC classes (i.e. not included in S-57 Product Specification for ENC) they shall be treated as members of unknown object classes. There will be no appropriate entry in the look-up tables but all objects shall be presented on the ECDIS screen. The occurrence of such an object shall be logged during transformation from ENC to SENC as an anomaly and the unknown objects shall be displayed using the question mark symbol QUESMRK1 as per section 10.3.3.4. 10.1.2 Unknown or Missing Mandatory AttributesAll mandatory attributes required by S‑57 Appendix B1, ENC Specification should be populated, except for cases where S‑57 Appendix B1 Annex A, Use of the Object Catalogue, deliberately codes by omission (e.g., clauses 5.8.2 and 10.2.1.1). In reality, sometimes the attribute values may not always be available and a producer may encode the attribute value as unknown. S-57 defines how null/unknown and missing attributes are encoded within ENCs. It should be noted that a missing attribute is not “unknown”. The Presentation Library provides default symbolization for many cases of attribute value omitted (e.g., in the first line for every object class in the look-up table). 10.1.3 Data OverlapsThe S-57 Product specification for ENC prohibits data overlaps in ENC cells of the same usage band. “Cells with the same navigational purpose may overlap. However, data within the cells shall not overlap. Therefore, in the area of overlap only one cell may contain data, all other cells shall have a meta object M_COVR with CATCOV = 2 covering the overlap area. This rule applies even if several producers are involved”. Despite the best efforts of the IHO, there are still some areas of the world where ENC overlaps exist. Where an overlap of two or more cells exists the ECDIS shall only display one cell for the overlap area and provide a permanent and persisting indication “overlap”. 10.1.4 GapsS-57 Use of the object catalogue edition 3.0.0 states; “There must be no gaps in data between adjoining cells of the same Navigational Purpose”. Despite the best efforts of the IHO, there are still some areas of the world where gaps in ENC coverage exist. Where gaps in ENC data of the same navigational usage exist smaller scale data from the SENC may be used to fill the gap. If there is no smaller scale data available the gap shall be filled with the no data area fill pattern. 10.1.5 No Data CoverageIMO Performance standards states; 6.1 ECDIS should provide an indication if: the information is displayed at a larger scale than that contained in the ENC; or own ship’s position is covered by an ENC at a larger scale than that provided by the display. IHO Specifications for ECDIS chart content and display S-52: An indication "refer to the official chart" is required if the display includes waters for which no ENC at appropriate scale exists. If a scale boundary is shown on the display, the information in an overscale area should be identified, and should not be relied on. A graphical index of the navigational purpose of available data should be shown on demand. Download 7.92 Mb. Share with your friends:
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