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Understanding French Map Information


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Hi Everyone


Again, apologies for writing in English on a French site. On a recent trip to France we used a large scale map (randonne ?) that was stated to be GPS compatible. There appear to be two sets of numbers, one in black and one in blue. My French is not good enough to work out the technical print at the side of the map.


My problem was that no matter which units I selected on my GPS (Garmin Summit) I could not replicate the numbers at the side of the map. The scale of the map was so large that the markings for the 'degrees and minutes' scale were a long way apart and made approximate location a little more complicated - small errors made for a lot of pain on a bike in the Cevennes. These other numbers appeared to be on a much smaller scale so the approximate location could be more accurately determined.


Is it possible to use these other numbers in combination with a GPS, and if so, what units should I select on my GPS ? (.....or is my Frech so poor I have completely missed the mark and should stick to cafe au lait et pain au chocolat s'il vous plait)

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The "GPS-compatible" maps are so called because, compared to the older ones, they now have UTM grid squares every 6-7cm. Previously, the grid squares were 10cm or more apart, and were based on the proprietary French grid system.


If you set your GPS into "UTM UPS" (that's what Garmin calls it, anyway), with the WGS84 datum, you should find that the maps match your GPS quite nicely.


And if you're caching, several Garmin units allow you to display UTM and "ddºmm.mmm" in two fields simultaneously.

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