The ECDIS has 2 categories of chart symbols; Traditional and Simplified symbols.
ECDIS can display chart symbols in either traditional or simplified form. Traditional symbols are very much like those used for the paper chart, whilst the simplified version has been designed for optimal display on a screen. The traditional symbols, as described in S-52, are often quite basic, and so some ECDIS manufacturers have made some improvements. For example, some manufacturers have added colour to buoys.
Simplified symbols
When this mode of display is selected, some of the symbols are very different from the paper chart. This mode also introduces some new symbols representing features introduced for ECDIS, such as the daymark. The simplified symbols are primarily used for the display of buoys and beacons.
Traditional symbols
When this mode of display is selected, the symbols will look more like those which appear in paper charts although in many cases they will still be simplified versions to take account of the limitations for displaying these features on screen rather than in print. They may therefore look like rather basic versions of the paper chart symbols, and the exact shape may vary slightly between different ECDIS types.
Note: All simplified point symbols are positioned on the centre of the feature, whereas traditional point symbols and paper chart symbols are positioned using the base of the symbol. This is why simplified chart display mode is preferred
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