IGN French user Grid setup information.
(Michelin info below)
> Does anyone know what the grid system is on the 1:100,000 France
> Topo maps made by IGN?
> for 1:25 000 map, but I suppose for 1:100 000 it's the same
> IGN use NTF datum (Nouvelle Triangulation de la France)
> on my GPS12, I use:
> - POSITION FRMT: USER GRID
> - MAP DATUM: USER (Clark 1880 ellipsoid,
> DX: -168 mt
> DY: -60 mt
> DZ: +320 mt
> DA: -112 mt
> DF: -0.5473884
> - original meridian is Paris and not Greenwich
> - offset Paris is 2° 20' 14.025" east
> - angles are in grades : 100 grades = 90
> 73's de F3UB
> N 47.47708° W 0.69014° [ ED50 ]
> N 47.47610° W 0.69146° [WGS84]
For a Michelin Map:
> Following is answer that I have recently received from Michelin web
> Projection system for French map at scale 1/200 000 (yellow series)
> Projection : Bonne (Conical)
> Ellipsoid : Plessis
> Origin : 2°20'14" E (Paris), 48°51'36"
N DX, DY, DZ in relation with
> WGS 84
> a = axis = 6376523 m
> f = flattening = 0.0032400188611
> DX = 1118 m
> DY = 23 m
> DZ = 66 m
> These data are for map Nr 51 à
89, 230 à 246
> N43° 15' 08"
> E05° 33' 25"
> Brian Spearing <email@example.com> a écrit dans
le message :
> > I want to set a few waypoints before a holiday in France, but the
> > 1cm=2km Michelin maps have a grid marked in *gr* units. These seem
> > be at 100km spacing for latitude, and less for longitude. I can't
> > any connection with UTM lat/long but 50gr looks close to 45deg
> > zero easting goes through Paris. Amazingly the key on the maps
> > no information, neither does the Michelin web site. The IGN 1cm=1km
> > maps have the same grid but marked almost unreadably.
> > Can anyone enlighten me please?
> > Brian.