Using GPS with IGN Walking maps

[Andyphilpott]

Has anybody been able to set up their GPS to work with the IGN Walking maps?

These maps indicate that they are GPS compatible and of course they can be used using the normal latitude and longitude datum (WGS84) but they also have blue data around the edge which is on a much larger scale related to kilometres. Being able to set up a GPS to use these would be far better and more accurate I think.

I am sure it must be quite straightforward but not grasped it yet.

Andy

[Quillan]

You have to change the units on the GPS from WGS84 to something else which I can't remember of the top of my head. I just went through the settings till I found the one that worked. These maps are available electronically for Palms and Pocket PC's either with or without GPS units and are marketed by Bayo and cost aroud 39€ per map including software and they are very good.

The problem I found with using a normal GPS and the maps is the accuracy especialy if you are using tracks and not proper walking signed walking routes. The tracks often change and it can be confusing. Hope this helps.

[Philipfry]

>I am sure it must be quite straightforward but not grasped it yet

Neither have I. However in my case this could be due to the fact that my GPS is now rather 'elderly' - in terms of these gadgets! It is a Garmin 12, and I know it includes the Swiss Grid, plus others, including of course those for both Britain and Ireland. I've used it in both countries, and unlike Quillan have always found the position it gives to tie in dead accurate to a known position on the map.

Of course, in addition to the display information, the map needs a 'grid' to be usable. At the moment I do not have a IGN 1:25000 (Blue cover) - or 'walking maps' as you term them to hand, so cannot check whether the 'blue data' is gridded, I don't think so. If that is the case then you would certainly not be alone in your difficulty - even if you did use the very latest GPS.

Philip

[Jonzjob]

I have just sent an e-mail to IGN and asked the question of what to set the GPS to. IF I get a reply I will post it here and let everyone know, 'cause I don't know either?

John.

[Born_to_fish_68<P><IMG src="http:forums.livingfrance.comimagesline.gif"><BR>Born_to_fish_68 (AKA Paul)<P><P>North Yorks House 16 Lakes 24<BR><P>]

The main problem with France is that they made their own meridian going through Paris rather than Greenwich and they used Lambert's conformal conic which makes all the mid-latitude areas (which was where the French had dominance) look really big.

On the Map it tells you what information was used to put the map together and which settings you need for Datums.

I have 2 IGN maps one for both the area of the house and one for the area of the Lakes we own and both have the same information.

"Les deux echelles du latitudes du cadre et les deuz chiffraisons kilometriques correspondent respectivement: - vers l'interieur, aux latitudes et longitudes en grades (longitudes referees au meridian de Paris) rapportees au systeme geodeesique francais NTF; les amorces sont celles du quadrillage kilometrique Lambert zone II etendu.

- vers l'exterieur, aux latitudes et longitudes en degres (longitues referees au meridian international) rapportees au systeme geodesique mondial WGS84 ou RGF93:  les chiffraisons bleues en italique en regard du quadrillage kilometrique sont des coordonnees Mercator Transverse Universal fuseau 31."

In english via babelfish

"The two scales of the latitudes of the framework and the deuz kilometric chiffraisons correspond respectively: - towards the interior, with the latitudes and longitudes in ranks (longitudes referees with the meridian of Paris) rapportees to system geodeesic French NTF; the starters are those of the squaring kilometric Lambert zone II etendu. - towards the exterior, with the latitudes and longitudes in degrees (longitues referees with the international meridian) rapportees with system geodesic world WGS84 or RGF93: the blue chiffraisons in italic compared to the squaring kilometric are coordonnees Transverse Mercator Universal spindle 31"

Basically you can select WGS84 but you need to use the Lambert II datum

or you can use WGS84 with UTM (Universal Transverse Mercator) to stay on the outer GPS coordinates. (This is better as the grid squares match this).

hope this helps if you need anything either technical or not or help setting up your GPS I will do what I can.