France IGN Maps "GPS ready" - what does it mean?

[BobM]

I have just bought IGN maps for the Via Francigena (Top 100 Series, 1:100,000).

The maps are gridded at 5km intervals and every second grid line is labelled. For example, one vertical grid line on the Map 101 is labelled "GPS 430".

There are also the usual latitude and longitude lines, but they don't agree with the GPS grid lines. For example, the logitude line right next to the "GPS 430" line is 2degrees.

What does all this mean?

Puzzled :?

Bob M

 

[backpack45scb]

Bob, those are UTM grid lines. Many people with gps devices set them to use utm rather than lat & long. Search and rescue units use utm. The advantage for me is that I can look at a decimal utm reading on my gps, and easily estimate where I am on my paper map, since my map utm grid lines are a decimal distance apart, rather than 12ths or 60ths or whatever lat & long is. Trust me, it's easier.

 

[BobM]

That makes sense. I did not realise you could choose different coordinate systems on a GPS unit. I must check if my car GPS has a UTM option. It certainly has an option for decimal degrees, rather than conventional "degrees-minutes-seconds"

Thx for the explanation.

Bob M

 

[BobM]

I did a bit more research by googling UTM coordinates. There are many useful websites, but here is one that is good for GPS novices like me. There are tutorials & a whole lot of good stuff.

http://www.maptools.com/UsingUTM/

The big plus is being able to very easily plot UTM coords on a "GPS ready" map.

If I take a GPS unit on the VF, it will be to check my position on the paper IGN maps when navigating away from the guidebook suggested route. The 1:100,000 IGN maps are pretty good at 1cm = 1km, but they lack detail for very accurate navigation away from guidebook routes. That's where UTM will be a blessing on UTM-gridded maps.

Here is another Garmin-friendly website that discusses navigating with tracks that I found useful:
http://gpstracklog.com/2010/07/navigati ... helds.html

BTW, I checked my automotive Garmin Nuvi & it does not seem to have UTM as a coordinates option - unless it is buried away in some obscure setting that I can't find. Garmin Hiking GPS units like the Dakota 20 apparently do.

Rgds

Bob M

 

[DavidCanadian]

I am planning to start the Via Francigena in September. I understand it is not well signposted in France. I would like to take a GPS handheld to help us to stay on course. Others have spoken highly of the Garmin Dakota 20 and the Garmin Oregon 450.The challenge to this GPS novice is to get the maps to load onto the device (Cdn topo maps are available in Canada - have not yet found a source for the French IGN maps.) and to then load the GPZ files that will put the VF trace on the IGN map.
I would love to hear from others who have used a GPS on the VF route in France and any advice/guidance they might offer especially on loading and using IGN maps and where they obtained them in digital format.

 

[mspath]

...
I would love to hear from others who have used a GPS on the VF route in France and any advice/guidance they might offer especially on loading and using IGN maps and where they obtained them in digital format.

David,

Try this web site for IGN digital maps. >> http://www.memory-map.co.uk/maps_france_onland_top25.htm

Also check out the web site of fellow Forum member Peter Robins who has done a great deal of work with and on digital maps. Here is that link >> http://maps.peterrobins.co.uk/

Good luck with your research and Buen Camino!

Margaret

 

[DavidCanadian]

Thank-you Margaret,

The Memory-Map site seems to be what I need. Have you used a GPS on your Caminos? This will be our first Camino that is not in the direction of Santiago.

David

 

[newfydog]

I used those UTM gridlines all the time until the gps units became so good at loading a long track log. Now I have the entire trail on the gps screen and a little triangle which tells you where you are on it.

If your map has the trail---most of them are on the IGN maps--you'll instantly know where you are by the shape of the track.

Look at the whole picture so you see the map and the screen---the map has UTM grids 18 19 20 etc, which are useful as kilometer scales, but the track on the map and the GPS match up so well that looking at the UTM or lat long numbers is not needed.