Maps Grids

I am new to GPS, and have discover that if I want to use paper maps,
then I will need to establish the grid on which the map is based.

Do the majority of GPS handhelds (Garmin 60C particularly) include all
the grid and datums that I am likely to encounter on maps in Europe
and Asia ? Is there a list of these anywhere ?

Can anyone recommend good cycling maps that include such grids to
cover Alsace in France ?

Many thanks for help
Dave

"David" wrote in message
om...
I am new to GPS, and have discover that if I want to use paper maps,
then I will need to establish the grid on which the map is based.

Do the majority of GPS handhelds (Garmin 60C particularly) include all
the grid and datums that I am likely to encounter on maps in Europe
and Asia ? Is there a list of these anywhere ?

You should be able to select the grid from a menu of grids in the set
up mode. Have a look around this site

http://gpsinformation.net/

--
Simon Mason
Anlaby
East Yorkshire.
53°44'N 0°26'W
http://www.simonmason.karoo.net

The datum for a particular map is usually printed on the map.

I have an old Magellan 315 and that has lots of different datums and a user
defined datum, so I'm sure a more modern gps will have what you need. You
might also be intersted in looking at www.gpsu.co.uk

Regards,
Neil

in message , David
') wrote:

I am new to GPS, and have discover that if I want to use paper maps,
then I will need to establish the grid on which the map is based.

Do the majority of GPS handhelds (Garmin 60C particularly) include all
the grid and datums that I am likely to encounter on maps in Europe
and Asia ? Is there a list of these anywhere ?

The IHO have a list of those used on marine charts, yes (although I
can't find it just now). A number of different ellipsoids and datums
are used because the earth is not a perfect elipsoid and different ones
are better approximations in different parts of the world (furthermore,
the earth isn't solid, it's squishy, and bits of 'solid earth' like for
example Britain move up and down with respect to the centre of the
earth by about one metre in the course of a normal day).

The OS grid has uses an ellipsoid called Airy1830 which as far as I know
is special and not used for anything else (there's also an ellipsoid
called OSGB30 which may be the same as Airy1830 but I can't find
anything which explicitly says so). Differences between ellipsoids can
lead to errors of position of up to about 250 metres.

I suspect that many if not most commercial land maps are not
sufficiently accurate for these differences to matter, particularly in
less developed and less populated parts of the world.

A useful introductory document is he
URL:http://www.gps.gov.uk/additionalInfo/images/A_guide_to_coord.pdf

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

'graveyards are full of indispensable people'

(David) wrote in
om:

I am new to GPS, and have discover that if I want to use paper maps,
then I will need to establish the grid on which the map is based.

Actually, there's a bit more to it than that.

Assume for a moment that your paper map has latitude/longitude
markings along the map's edges(neat lines). It might also have
a grid on the map that connects the lat/lon tick marks.

If you have your GPS on, and receiving signals, and set to
display it's position in lat/lon format, and you want to see
where that puts you on the paper map, you need to know what
datum(s) are being used. In practical terms, what this means
is reading the paper map to determine what datum it uses,
then setting your GPS to the same datum, then using the
position reported by the GPS.

Even if your paper map has lat/lon tick marks on the neat lines,
it may also have a grid printed on the map, such as a UTM
(Universal Transverse Mercator) grid. To make use of this
grid you still need to be using the correct datum in your
GPS. You just change your GPS's "position format" setting
from lat/lon to, in this example, UTM, and then read your
position in UTM coordinates and use them in conjunction
with the map's UTM grid.

Although it's a bit 'US-centric', you might be interested
in Garmin's "Using a Garmin GPS with Paper Maps" manual.
There's a link in the "GPS Resources" section on the
GPS page on my website.

--
Dave Patton
Canadian Coordinator, Degree Confluence Project
http://www.confluence.org/
My website: http://members.shaw.ca/davepatton/

David wrote:

I am new to GPS, and have discover that if I want to use paper maps,
then I will need to establish the grid on which the map is based.

Do the majority of GPS handhelds (Garmin 60C particularly) include all
the grid and datums that I am likely to encounter on maps in Europe
and Asia ? Is there a list of these anywhere ?

Can anyone recommend good cycling maps that include such grids to
cover Alsace in France ?

Many thanks for help
Dave
You can visit our website on http://www.lesrandoactifs.fr.st dedicate to mountain bike in south of france
Visit to http://www.ign.fr
if you dont found your answer on the site mail us .

best regards

LUC

"David" wrote in message
om...
I am new to GPS, and have discover that if I want to use paper maps,
then I will need to establish the grid on which the map is based.

Do the majority of GPS handhelds (Garmin 60C particularly) include all
the grid and datums that I am likely to encounter on maps in Europe
and Asia ? Is there a list of these anywhere ?

Can anyone recommend good cycling maps that include such grids to
cover Alsace in France ?

Many thanks for help
Dave

Andy

You have drawn several replies about grids.

For maps I suggest that you look at the Michelin 1:200 000 or newer 1:180
000 and 1:150 000 maps, which I have found quite satisfactory for cycling on
minor roads. I have a ten year old one with latitude and longitude gridlines
at 10' (ten minute) intervals. See http://www.viamichelin.com . These maps
are widely available in France at supermarkets and petrol stations. They are
also obtainable in UK at £3.99. One supplier is http://www.themapshop.co.uk/
..

For more detailed (and more expensive) maps, more like Britain's Ordnance
Survey maps, see the 1:25 000 maps of the French Institut Geographique
National http://www.ign.fr/ . The newer maps are marked Compatible GPS and
have UTM gridlines in blue using the datum WGS 84. I have used these maps
for skiing off the beaten track. IGN do summer and winter versions for some
of the alpine areas. I expect (but cannot confirm) that the summer ones
include pistes cyclables (cross country cycle paths). The maps typically
cost 9 Euro and are harder to find. In UK http://www.themapshop.co.uk/ sell
them.

Mark I

"Mark Illingworth" wrote in message ...
"David" wrote in message
om...
I am new to GPS, and have discover that if I want to use paper maps,
then I will need to establish the grid on which the map is based.

Do the majority of GPS handhelds (Garmin 60C particularly) include all
the grid and datums that I am likely to encounter on maps in Europe
and Asia ? Is there a list of these anywhere ?

Can anyone recommend good cycling maps that include such grids to
cover Alsace in France ?

Many thanks for help
Dave

Andy

You have drawn several replies about grids.

For maps I suggest that you look at the Michelin 1:200 000 or newer 1:180
000 and 1:150 000 maps, which I have found quite satisfactory for cycling on
minor roads. I have a ten year old one with latitude and longitude gridlines
at 10' (ten minute) intervals. See http://www.viamichelin.com . These maps
are widely available in France at supermarkets and petrol stations. They are
also obtainable in UK at £3.99. One supplier is http://www.themapshop.co.uk/
.

For more detailed (and more expensive) maps, more like Britain's Ordnance
Survey maps, see the 1:25 000 maps of the French Institut Geographique
National http://www.ign.fr/ . The newer maps are marked Compatible GPS and
have UTM gridlines in blue using the datum WGS 84. I have used these maps
for skiing off the beaten track. IGN do summer and winter versions for some
of the alpine areas. I expect (but cannot confirm) that the summer ones
include pistes cyclables (cross country cycle paths). The maps typically
cost 9 Euro and are harder to find. In UK http://www.themapshop.co.uk/ sell
them.

Mark I

-------------------------------

If you use maps that have a scale of 1:100,000 or smaller (1:250,000)
the particular "datum" of a country is more or less only an academic
point of interest. The larger the scale of your map (IGN or Ordnance
Survey), the more important the datum details become. The UK, Italy
and Germany use a Transverse Mercator projection that a Garmin will
accommodate. The Garmin will of course accommodate UTM. However,
most other countries in Western Europe do NOT use the Transverse
Mercator on large-scale maps and therefore the Garmin units are
useless except for plotting latitude and longitude coordinates on
those maps. Local Grid systems based on the oblique stereographic and
the Lambert conformal conic are only attainable with a Magellan -
Garmin won't do it.

If you stay with small-scale maps, such minutiae can be ignored.

Cliff Mugnier
LOUISIANA STATE UNIVERSITY

"Prof. Cliff Mugnier" wrote:

The UK, Italy
and Germany use a Transverse Mercator projection that a Garmin will
accommodate. The Garmin will of course accommodate UTM. However,
most other countries in Western Europe do NOT use the Transverse
Mercator on large-scale maps and therefore the Garmin units are
useless except for plotting latitude and longitude coordinates on
those maps. Local Grid systems based on the oblique stereographic and
the Lambert conformal conic are only attainable with a Magellan -
Garmin won't do it.

This is also true for State Plane coordinates in the US, see:
http://www.gpsinformation.net/state-plane-mag.html
--
Jack

Get general GPS information at: http://www.gpsinformation.net/