A raster-scanned electronic chart is like an electronic snapshot of a paper chart. On-screen it looks just like the same familiar paper charts you've used for years. If you're using a color monitor, you'll usually see the original colors from the paper chart, though SoftChart uses a slightly different color palate. Raster charts are produced by Maptech and SoftChart in the United States, NDI in Canada, British Admiralty in England and by official hydrographic offices in a number of other countries. Although raster charts normally run on computers some dedicated plotters that raster charts. Raster charts are available in geographical groups and are distributed on CD-ROM.
Here is a example of a Raster Chart...
Vector charts are distillations of genuine paper charts, but their presentation is different. Vector charts can have virtually the same information as their raster equivalents. Until recently, vector charts were usually displayed on dedicated plotters with monochrome displays, but today more manufacturers are making plotters with color displays and much improved feature sets. The most popular vector charts (for plotters) in the world are made by C-Map and Navionics, and they come on proprietary cartridges.
Vector charts are also now available for computer-based electronic charting systems. Nobeltec, Transas Marine and MaxSea are all programs that use vector charts. Vector displays can allow you to view all or select "layers" of information to reduce clutter or add detail to your chart. And the depth soundings and other information are always very readable - no matter the scale or rotation of your chart. There are many other advantages. We like vector cartography and we and think you will too!
An Example of a Vector Chart....
Which is best? Chart publishers argue about whether vector charts are better than raster charts or vice versa when running on a computer. We feel that each type has its advantages, and either type can serve you very well. In making your choice, consider the following:
- Type of boat? First, what type of boat do you have? Vector charts can be displayed on dedicated plotters. Unlike most PCs, most plotters are marinized and can be weatherproof. Most operate on 12 volts, and many have screens that allow operation in bright sunlight—features you rarely find on a PC.
Typically, we find that skippers of boats less than 40 feet tend to prefer dedicated plotters using vector charts, while those with boats over 40 feet tend to prefer PC-based chart systems. However, there are many exceptions.
- Appearance? Second, what kind of chart do you want to look at? If you demand one that looks exactly like a paper chart, then you'll want raster charts. Keep in mind, however, that C-Map, Passport and Transas vector charts look very much like what you see on a paper chart, especially when displayed on a color computer screen. Plotter screens are usually smaller than computer screens, which can make them more difficult to read. Ultimately the decision might hinge on what looks best to your eye.
- Cost? The total cost includes the computer or plotter, the software, and the electronic charts. Generally, raster and vector charts that run on computers provide much more coverage for the dollar than do charts for dedicated plotters. However, chart plotters can be less expensive (and if so less capable) than the laptop computers used for electronic charting. Also, installation costs for both have to be considered.
Final Analysis: When you're ready to buy an electronic charting system take the time to look at both vector and raster solutions. If you'd like some advice, ask one of our electronic charting experts. Since we don't sell the systems and do sell both vector and raster charts, we have no bias.