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   See The Difference:
Some Benefits of Vector Charts

VECTOR CHART running on Visual Navigation Suite. Note chart clarity and detail, orientation of descriptions and soundings and object properties.

There are significant differences between raster and vector chart technologies. As with many things in electronic charting, you must see them to appreciate the differences.
        This web page graphically displays some of the differences between quality vector charts and traditional raster charts. The image to the right is a vector chart running on a prototype version of Visual Navigation Suite. The image below and to the left, is a traditional raster chart (for the same area) also running in Visual Navigation Suite. Those that are from the Northwest will recognize the area displayed as the entrance to the Hiram M. Chittenden locks in Seattle, WA. In both cases examples, Visual Navigation Suite is running in CourseUp mode.
        The first thing to notice is the clarity of the vector chart. Due to their mathematical nature, vector charts remain sharp and clear at all zoom levels or orientations (NorthUp, CourseUp or NativeUp). You will note the traditional raster chart below is significantly more fuzzy (even with CrystalView turned on) than the equivalent vector chart. While some vector chart databases lack detail, you will notice the chart to the right is highly detailed. As announced at the 1999 Miami Boat Show, Nobeltec has entered into a strategic alliance with Transas Marine. Transas among other things produces high quality, commercial grade vector charts.
        Another thing to note, is the orientation of the descriptions (for example, "Shilshole Bay") and soundings on the vector chart. Even though the program is running in CourseUp mode, the soundings and descriptions are readable and facing the user. You will note on the traditional raster chart below, the descriptions and soundings are upside down because the program is running in CourseUp mode. Related to this, note that the soundings on the vector chart are in meters. Due to a vector chart's "intelligent nature", it is possible to display soundings and other numerical data in whatever measurement units the user prefers (fathoms, feet, meters, etc).
        Unlike raster charts, vector charts are a database of objects and information. Given this, it is possible for users to easily retrieve information from the vector chart database. For instance, in the vector example above, you can see a yellow box that has latitude and longitude information and the words "Anchorage Prohibited" in it. This box was displayed when I held my cursor over the Anchorage Prohibited (anchorproh.jpg (473 bytes)) symbol.   

Traditional RASTER CHART running on Visual Navigation Suite. Note: Lack of clarity, upside-down soundings & descriptions.

The same concept holds true for other objects on a vector chart (buoys, lights, bridges, navigation symbols, etc) -- hold your cursor over the object, and any relevant information will be displayed. This feature makes it much easier for the mariner to decipher the various symbols used on marine charts.
        Those that have used vector charts in the past are undoubtedly familiar with a vector chart's ability to hide and display different "layers". Layers include things like depth contours, land features, navigation aids, etc. The ability to hide or display different layers makes it easier for the mariner to only display the information that is relevant to him/her.

Raster vs Vector Charts

Raster scanned charts are direct video images of paper charts. They are faithful copies of the paper versions, with all the detail of a paper chart. Vector charts, like the products from Garmin, C-Map and Navionics have the information transformed into coordinates in a data file, placed at different levels in the memory of the machine. You can choose to view some levels but not others and see only what is needed, and the data is compressed to take up less space. Icons, numerals and words appear in a “heads up” orientation. Vector charts are “object oriented”, so when a cursor is positioned over a navigational aid or other feature, additional data windows pop up.

Overview of Electronic Vector Chart and Raster Chart Development. It is important when discussing or viewing charts on a computer screen to know what the format is. There are currently two formats of electronic charts available: raster (RNC) and vector (ENC).

The Raster chart is an electronic chart representation in one level of paper chart. In that respect all the information shown on the chart is displayed on a dedicated electronic chart unit screen. A raster chart is produced by scanning a paper chart or a print master and is made up of a number of lines which, in turn, are created by a number of picture elements (pixels). Being constructed in this way a computer cannot recognize an individual feature on the chart, such as a sounding, and the data is not interactive live as on a vector chart. Raster format charts are not as expensive to produce as vector charts and the technology involved has been in use for many years.

The Vector chart is far more comprehensive. These are interactive charts, built up in layers of information, and are produced by digitally capturing individual charted objects and their attributes, based on geographical positions. This information is stored in a database which, for instance, may contain the details of a sectored light at a certain position. This will include its colour and light characteristic. As the vessel comes in range of the light, the light turns on and, as the vessel crosses the light sectors, the light changes colour. The vector display allows the information to be customized, such as the facility to turn off certain information such as names, whilst allowing for important additional user information to be displayed. Vector data is deemed "intelligent" or "live" data. Vector format is state of the art and represents the future in electronic navigation.








Sport Phillip Marine services the boating, yachting & fishing needs of the Mornington Peninsula from Frankston, Daveys Bay, Mt. Eliza, Mornington, Mt. Martha, Safety Beach, Martha Cove, Dromana, Rosebud, Rye, Blairgowrie, Sorrento and Portsea on Port Phillip Bay to Yaringa, Warneet, Somers, Hastings, and Flinders on Westernport Bay.




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