GPS - Position Format/Datum for use for hiking in France

Author

Position Format/Datum for use for hiking in France

Rob

2007-05-22, 12:33 pm

Hi,

I need to set up Position Format and Mat Datum for an upcoming trip to
France. Presumably it isn't British Grid/Ord Srvy GB as it is in the UK?

I don't see any obvious options in the list on my device. I also cannot see
any information on the maps we plan to use for walking/hiking, but that
could possibly be because my French is schoolboy to say the least.

Any ideas? The map is a 1:25000 1cm=250m and all the maps are from the Carte
De Randonnee series. Would UTM-WGS84 be correct? Or is there some
user-defined numbers that would be better?

Many thanks

Alan White

2007-05-22, 3:33 pm

On Tue, 22 May 2007 16:27:56 GMT, "Rob" < dontsendmeanyjunk@nt
lworld.com>
wrote:

>Would UTM-WGS84 be correct?

Yes.

--
Alan White
Mozilla Firefox and Forte Agent.
Twenty-eight miles NW of Glasgow, overlooking Lochs Long and Goil in Argyll, Scotland.
Webcam and weather:- http://windycroft.gt-britain.co.uk/weather

CRet

2007-05-22, 10:33 pm

Hi,

There are 4 map coordinate systems on a french IGN 1/25.000 Topo map

Newest map only have a blue grid which correspond to UTM (WGS84) system.
These map are clearly indicating a large "Compatible GPS" advertising on it.
These maps are easely recognised by the large blue overlay grid (1000x1000m
grid) on it. These newest map with GPS blue kilometric grid overlay are
rather new and have been introduced only 5-6 years ago. The blue overlay
grid is UTM in WGS84 system to make easy use of GPS.

Other map, without blue grid overlay only indicates map coordinates in the
margin. There are several indications there, each correspond to a different
geodesic system.

-1- In the four corners of the map, longitude and latitude are indicated in
sexadecimal degree using italic font. (dd° mm' ss" ex.: 47°20'27") into the
ED50 (European 1950) system (Ellipqoïde de Clarck). The meridian of
reference is the GREENWICH meridian.

-2- In the margin, at the outside part of the scale, black italic font
indicate kilometric plane UTM coordinate into the ED50 (European 1950)
system. Only the tick on the scale indicate position of the UTM, no grid go
trougth the map.

-3- The lat and lon are indicated in decimal grad (400 gr = 360° ). The
corresponding meridians and parallels are draw trought the map in thin black
line. Note that the border of the map is also indicate in grad. The NTF
system is use for these graduation.
Beware, the reference 0 gr meridian is the meridian of PARIS, not of
GREENWICH as in the WGS84 system. (Sorry for that, but you have to
understand that this french geodesic system was intiate during Napoleon
Bonarparte's wars again Great Britain. At this time, it was impossible to
build up to a system with GREENWICH meridian as a reference. :-)
The longitude offset between the two is 2° 20' 14.025" which have to be add
to NTF grad longitude (after conversion in degree).

-4- In the margin, at the insisde part of the scale, the planar kilometric
Lambert coordinates are indicated in the NTF system. There is mainly three
type of Lambert projection (Lambert I, II and III) used respectively for the
north, middle and south of France. The text in the map legend indicates
which Lambert projection was used to draw the map. The extanded 'Lambert
étendu' projection is only use on maps covering the whole (or a large part)
of the territory. These last projection isn't used on topographic map at
1:25.000 scale.

On all the topo map, indications are explain (in french) wich figures
correspond to which system. If you are in trouble, don't hesitate to send my
a copy of the explaination, I will try to translate it at least in my broken
english. Legend also indicates any change from the standard systems and
coordinates

In conclusion :

If you have a "compatible GPS" map (the newest edition), you are a lucky
man. And you may used your GPS easely.

If you have an older version of the IGN french topo map , then you are in
trouble. If your GPS may have the European 1950 or the NTF system, you have
better to make a test and using it. If not, you have to setup your GPS with
'user customised system' is available.

The transformation parameters from NTFS to WGS84 are
(http://www.ign.fr/telechargement/ed...oordonn%E9es.pd
f)
TX = -168m TY= -60m TZ=+320 m (precision of a few
meters).

In order to help you checking your setup, I give there the coordinate of one
point in the est of France in the several coordinate systems :

System Long
Lat
NTF (reference meridian Paris) 6 gr 54 gr
NTF (reference meridian Paris) 5.40000° 48.60000°
NTF (reference meridian Greenwich) 7.73723° 48.60000°
NTF (reference meridian Greenwich) 7°44'14.0 48°36'00.0"
ED50 (reference meridian Greenwich) 7°44'16.4" 48°36'03.0"
WGS84 7°44'12.2"
48°35'59.9"

ED50 (UTM zone 32 north) 406 946 m 5 383 958 m
WGS84 (UTM zone 32 north) 406 864 m 5 383 757 m

NTF Lambert I (use for north of France) 997 960m 114 185m
NTF Lambert IV (étendu) 998 137m 2 413 822 m

Hope this help you check your GPS setup !

Good luck. And have a nice journey in France.

C.Ret

System Associated ellipsoïd a b
1/f e
NTF Clarke 1880 IGN 6378249.2 6356515.0
293.466021 0.08248325676
ED50 Hayford 1909 6378388.0 6356911.9461
297.000000 0.08199188998
WGS84 IAG GRS 1980 6378137.0 6356752.314
298.257222 0.08181919106

"Rob" < dontsendmeanyjunk@nt
lworld.com> a écrit dans le message de
news:gSE4i.159$rQ4.3@newsfe1-win.ntli.net...
> Hi,
>
> I need to set up Position Format and Mat Datum for an upcoming trip to
> France. Presumably it isn't British Grid/Ord Srvy GB as it is in the UK?
>
> I don't see any obvious options in the list on my device. I also cannot
see
> any information on the maps we plan to use for walking/hiking, but that
> could possibly be because my French is schoolboy to say the least.
>
> Any ideas? The map is a 1:25000 1cm=250m and all the maps are from the
Carte

> De Randonnee series. Would UTM-WGS84 be correct? Or is there some
> user-defined numbers that would be better?
>
> Many thanks
>
>

Alan White

2007-05-23, 4:33 am

On Wed, 23 May 2007 00:17:37 +0200, "CRet" <c.ret@wanadoo.fr> wrote:

>-2- In the margin, at the outside part of the scale, black italic font
>indicate kilometric plane UTM coordinate into the ED50 (European 1950)
>system. Only the tick on the scale indicate position of the UTM, no grid go
>trougth the map.

But it's very easy to create the grid by using a long straight edge, a
fine pen and by joining corresponding UTM ticks. I've used this method
on a number of maps.

--
Alan White
Mozilla Firefox and Forte Agent.
Twenty-eight miles NW of Glasgow, overlooking Lochs Long and Goil in Argyll, Scotland.
Webcam and weather:- http://windycroft.gt-britain.co.uk/weather

CRet

2007-05-23, 4:33 am

You are right.

"Alan White" <alan.lesley@ukgateway.net> a écrit dans le message de
news:j2s7535ilij2s9r
k3jse0ot1gu349jj49o@
4ax.com...
> But it's very easy to create the grid by using a long straight edge, a
fine pen and by joining corresponding UTM ticks. I've used this method on a
number of maps.

Core2Duo

2007-05-23, 10:33 am

CREt,

you're a wealth of knowledge.

Is it the same situation w/ Portugal as you described for France?.

"CRet" <c.ret@wanadoo.fr> wrote in message
news:46536cd2$0$2738
8$ba4acef3@news.orange.fr...
> Hi,
>
> There are 4 map coordinate systems on a french IGN 1/25.000 Topo map
>
> Newest map only have a blue grid which correspond to UTM (WGS84) system.
> These map are clearly indicating a large "Compatible GPS" advertising on
> it.
> These maps are easely recognised by the large blue overlay grid
> (1000x1000m
> grid) on it. These newest map with GPS blue kilometric grid overlay are
> rather new and have been introduced only 5-6 years ago. The blue overlay
> grid is UTM in WGS84 system to make easy use of GPS.
>
> Other map, without blue grid overlay only indicates map coordinates in the
> margin. There are several indications there, each correspond to a
> different
> geodesic system.
>
> -1- In the four corners of the map, longitude and latitude are indicated
> in
> sexadecimal degree using italic font. (dd° mm' ss" ex.: 47°20'27") into
> the
> ED50 (European 1950) system (Ellipqoïde de Clarck). The meridian of
> reference is the GREENWICH meridian.
>
> -2- In the margin, at the outside part of the scale, black italic font
> indicate kilometric plane UTM coordinate into the ED50 (European 1950)
> system. Only the tick on the scale indicate position of the UTM, no grid
> go
> trougth the map.
>
> -3- The lat and lon are indicated in decimal grad (400 gr = 360° ). The
> corresponding meridians and parallels are draw trought the map in thin
> black
> line. Note that the border of the map is also indicate in grad. The NTF
> system is use for these graduation.
> Beware, the reference 0 gr meridian is the meridian of PARIS, not of
> GREENWICH as in the WGS84 system. (Sorry for that, but you have to
> understand that this french geodesic system was intiate during Napoleon
> Bonarparte's wars again Great Britain. At this time, it was impossible to
> build up to a system with GREENWICH meridian as a reference. :-)
> The longitude offset between the two is 2° 20' 14.025" which have to be
> add
> to NTF grad longitude (after conversion in degree).
>
>
> -4- In the margin, at the insisde part of the scale, the planar kilometric
> Lambert coordinates are indicated in the NTF system. There is mainly three
> type of Lambert projection (Lambert I, II and III) used respectively for
> the
> north, middle and south of France. The text in the map legend indicates
> which Lambert projection was used to draw the map. The extanded 'Lambert
> étendu' projection is only use on maps covering the whole (or a large
> part)
> of the territory. These last projection isn't used on topographic map at
> 1:25.000 scale.
>
> On all the topo map, indications are explain (in french) wich figures
> correspond to which system. If you are in trouble, don't hesitate to send
> my
> a copy of the explaination, I will try to translate it at least in my
> broken
> english. Legend also indicates any change from the standard systems and
> coordinates
>
>
> In conclusion :
>
> If you have a "compatible GPS" map (the newest edition), you are a lucky
> man. And you may used your GPS easely.
>
> If you have an older version of the IGN french topo map , then you are in
> trouble. If your GPS may have the European 1950 or the NTF system, you
> have
> better to make a test and using it. If not, you have to setup your GPS
> with
> 'user customised system' is available.
>
> The transformation parameters from NTFS to WGS84 are
> (http://www.ign.fr/telechargement/ed...oordonn%E9es.pd
> f)
> TX = -168m TY= -60m TZ=+320 m (precision of a few
> meters).
>
>
> In order to help you checking your setup, I give there the coordinate of
> one
> point in the est of France in the several coordinate systems :
>
> System Long
> Lat
> NTF (reference meridian Paris) 6 gr 54 gr
> NTF (reference meridian Paris) 5.40000° 48.60000°
> NTF (reference meridian Greenwich) 7.73723° 48.60000°
> NTF (reference meridian Greenwich) 7°44'14.0 48°36'00.0"
> ED50 (reference meridian Greenwich) 7°44'16.4" 48°36'03.0"
> WGS84 7°44'12.2"
> 48°35'59.9"
>
> ED50 (UTM zone 32 north) 406 946 m 5 383 958 m
> WGS84 (UTM zone 32 north) 406 864 m 5 383 757 m
>
> NTF Lambert I (use for north of France) 997 960m 114 185m
> NTF Lambert IV (étendu) 998 137m 2 413 822 m
>
> Hope this help you check your GPS setup !
>
> Good luck. And have a nice journey in France.
>
> C.Ret
>
>
>
>
>
>
> System Associated ellipsoïd a b
> 1/f e
> NTF Clarke 1880 IGN 6378249.2 6356515.0
> 293.466021 0.08248325676
> ED50 Hayford 1909 6378388.0 6356911.9461
> 297.000000 0.08199188998
> WGS84 IAG GRS 1980 6378137.0 6356752.314
> 298.257222 0.08181919106
>
>
>
>
> "Rob" < dontsendmeanyjunk@nt
lworld.com> a écrit dans le message de
> news:gSE4i.159$rQ4.3@newsfe1-win.ntli.net...
> see
> Carte
>
>

David Millen

2007-05-24, 7:33 am

On Tue, 22 May 2007 16:27:56 GMT, "Rob"
< dontsendmeanyjunk@nt
lworld.com> wrote:

>Hi,
>
>I need to set up Position Format and Mat Datum for an upcoming trip to
>France. Presumably it isn't British Grid/Ord Srvy GB as it is in the UK?
>
>I don't see any obvious options in the list on my device. I also cannot see
>any information on the maps we plan to use for walking/hiking, but that
>could possibly be because my French is schoolboy to say the least.
>
>Any ideas? The map is a 1:25000 1cm=250m and all the maps are from the Carte
>De Randonnee series. Would UTM-WGS84 be correct? Or is there some
>user-defined numbers that would be better?
>

You could also, if time and funds permit, get the relevant
CartoExploreur mapping on CD. I ordered one for western Ariege
earlier this month and it arrived within a week. Import and export
waypoints etc to/from your GPS, if that's your thing.
--
All the best
David Millen
Xativa, Valencia
www.fincacasablanca.com
please reply in group
if you have to email me, remove the obvious:
davidtheobvious@mill
en.com

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