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On Mon, 18 Sep 2006 07:45:00 -0400, "Gerald"
wrote: I am convinced that raster charts are the way to go and that, perhaps, I am not in the mainstream and have made it to the position of 'old-fart'. I hear you, vector charts definitely takes some getting used to, and for some things raster is clearly superior. For the last two years I've had both side by side, raster on PC/Maptech, and CMAP/vector on a Furuno chart plotter. I agree with much of what you say, but have come to appreciate some of the benefits of vector as well. One thing that vector does much better is "zoom in" and "zoom out". When you zoom a raster chart the text fonts and pixel details get larger and smaller also, which renders them illegible very quickly. Vector on the other hand automatically compensates for zoom level so that font sizes are constant, and detail pixels are adjusted to an appropriate size. The net result is that fewer vector charts are required for any given area since detail improves as you zoom in, unlike raster which requires an entirely new chart to show greater detail. The other area where vector is clearly superior, is "course up" mode. Course-up is a much more intuitve way to view chart data, particularly in close quarters. However, if you display raster charts "course up" on anything other than a north bound heading, chart text and symbols appear rotated out of the normal vertical orientation, and are actually upside down in south bound directions. With raster charts, the text and symbols are automatically rotated to stay in normal orientation, making course-up much more useful. On our boat I generally do all of my route planning on the PC using raster charts since Maptech is very good at that, and I can do everything off-line in the comfort of the main cabin the night before. While running I keep the PC zoomed out to show the big picture and the route information such as range/bearing to next waypoint, total miles, time-to-go, etc. On longer legs I will transfer the next waypoint details to the Furuno chart plotter as well. The chart plotter is usually left in course-up mode and zoomed in to a fairly high level of detail where chart symbols are resonably uncluttered and easily readable. Another superior feature of the chart plotter, unrelated to vector/raster, is screen brightness and clarity. The brightness level is fully adjustable for comfortable viewing all the way from direct sunlight to complete darkness. No PC or flat panel display that I have used has a comparable level of brightness or adjustability. With the right selection of features and options, the chart plotter has some other worthwhile attributes. For example our Furuno system has the ability to super impose radar data on top of the chart display which is very useful for identifying unkown radar blips and determinig whether or not it is a navaid or probable boat. Since this feature requires rotating and zooming the chart data to match the radar display, vector charts are clearly the right choice. |
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