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Setting Up Your Map If you just calibrated a raster map, open it in GPS MapEdit. If you're not using a raster map, run GPS MapEdit and import or add your first piece of data to begin. Here comes the trickiest part of the whole deal: levels. Levels determine which elements of your map show up at which zoom levels on your GPSr, and also the level of detail used to display elements at different zoom levels. For instance, when zoomed out to 80 mile range, you might see only highways and big lakes, and they'll be very simplified. Zoom in to 8 miles, and smaller roads may appear. Zoom into 1.2 miles and you'll start to see topo lines and creeks, etc., and they'll be highly detailed. If you have too many levels, your map will take up too much GPSr memory. If you have too few, it will look very jagged and not at all detailed at certain zoom levels. This usually requires some trial and error. To further complicate things, most GPSrs have different detail settings. These settings basically just change at which zoom settings your levels show up. You can't control how your users have their GPSr set up, so you just have to try to have settings that look good at the different detail settings. These settings also give your users some choice in when your map elements show up, which is a good thing. In Map Edit, you can have anywhere between 1 and 8 (I think) level settings. Each of those levels has a bit setting to determine how detailed your map elements are at that level. For instance, when zoomed way in, you want your trails to be very detailed because the user will be able to see it closely, and you can get away with having the high level of detail since there's not much area being shown on the screen. When zoomed out, you want the trail simplified since you won't be able to see it up close anyway, and you're going to make your poor GPSr start to heave if it has to draw tons and tons of very detailed lines. That means that with each level you have, another (simplified) copy of your elements is being stored, and therefore the file size of the map increases. Here's a table showing how the bit settings translate into how the map is displayed on your GPSr, and different GPSr detail setings (normal, more, and most):
It took me a lot of trial and error with different settings to find what made the map as compact as possible, allowed me to control when things appear, and made it look good at every zoom setting. Here's what I arrived at:
The last level (5) must be empty and it controls at which zoom level your map disappears and the GPSr goes back to displaying the base map. You assign levels to each of your map elements, which I'll cover next. |
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