Differences between Vector and Raster Charts

This page is inspired by: Bellingham Chart Printers

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 () 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.

See an animated GIF that demonstrates vector chart layer technology. The animated GIF cycles thru and displays an additional layer every 4 seconds. There are five layers in this example.

        This web page has shown you a mere sampling of the potential available with vector charts. Due to a vector chart's "intelligent" nature, a variety of exciting and useful features are possible

Benefits of Vector Charts

Vector Charts offer many benefits over other formats. Particularly Clarity, Precision and Power.

• Clarity - Clear at any orientation or scale setting, features are automatically filtered to show the best image possible.
• Precision - The charts are made directly from official navigation charts and also include up-to-date notice to mariner information.
• Power - Control how a chart is displayed on the screen, point the cursor at an object and more information is displayed. Vector charts also provide the opportunity for software features that require interaction with the chart.

These are just a few of the things that can be done with vector charts.

Some of the Strengths of Vector Charts include:

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 below, you can see a yellow box that has latitude and longitude information and the words "Anchorage Prohibited" in it. This box is displayed when the cursor is placed over the Anchorage Prohibited symbol.


Passport chart showing tooltip popup containing detailed information.

Clarity is the same regardless of orientation
Due to their mathematical nature, vector charts remain sharp and clear at all zoom levels or orientations (NorthUp, CourseUp or NativeUp). Notice how the old style raster chart below is significantly more fuzzy (even with CrystalView turned on) than the equivalent vector chart. You will notice the vector chart is highly detailed.


Split image showing side-by-side comparison of raster chart (left) and vector chart (right).

Text the same regardless of orientation
Note the orientation of the descriptions 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. On raster charts, the descriptions and soundings would be upside down when the program is running in CourseUp mode.


Chart image, north up.


Same chart image, course up. Note the text orientation is still right-side-up.

Data Filtering commands
Vector charts are often referred to as "intelligent" charts. For example, when using a vector chart, the navigator can turn on/off various layers (for example, the "depth contours layer" or the "lights layer").

The Passport Chart control toolbar is used to adjust the display of Passport Chart windows.

Passport chart with depth soundings turned on.

Passport chart with depth soundings turned off.

Depth units can be set by the user
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 in whatever measurement units the user prefers (fathoms, feet, meters, etc).

Soundings shown in feet.

Soundings shown in meters.

Active Lights
When navigating, it can be difficult to match a light seen from a vessel with those on the chart. The lights shown on Passport charts have additional information associated with them, such as the range and bearing from which they can be seen. Using this information, the software can change the way the light is shown depending on the vessel's position.

The yellow arrow in the upper left corner points to a light which is out of range to be seen at the boat's current position, so it is displayed as a dashed circle.

When the boat is within visible range of the light, the light is displayed in its proper (green) color.

Click Here to see an example of zoom levels to different scales.

Chart size
Vector charts are very size efficient compared to raster charts. It is possible to fit all of the charts for the entire world on one CD-ROM. The table below compares some sizes of Passport charts to NOAA/ChartKit charts.

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