Italian map - interpreting grid?

Terry

I have been through this one. It took me ages to suss it out. Italian maps
use Gauss Boaga datum and a central meridian which runs through Monte Mario,
an observatory near Rome. That's some obscure distance west of Greenwich
(12 degrees, 27 minutes and 8.4 seconds).

I don't believe that the grid you see is actually UTM. It's Italian
standard grid. The Italians divide their country into two zones East and
West of the meridian and I think the grid is relative to this.

After many weeks of frustration I finally invented a whole new MapMan
feature just to deal with Italian maps - which I called "Grid Systems". In
fact, if you download MapMan and look at the Help text for "Grid Systems"
you will find that it starts with a discussion of Italian walking maps.

MapMan's Grid System isn't essential for calibrating an Italian map but I
found it made the job easier. If you are using a different mapping
application then I would ignore the grid lines altogether and calibrate the
map using the degrees marked along the edges (but remembering to use Gauss
Boaga datum).

My attempts to calibrate my own Italian map were only moderately successful.
When I finally got to Italy I found that all my map items were about 200
feet out but as the error was constant and always in the same direction I
was soon able to mentally compensate. It would have been better if I'd
taken the computer with me to make the necessary adjustments "in the field"
but my other half usually vetoes taking laptops on holiday!

Regards
Keith

Terry Pinnell said:

46d 39m N is between 51|70 and 51|71
46d 33m N is between 51|60 and 51|61
12d 0m E is between 7|30 and 7|31

it's quite simlpe - the UTM values are in km, so you have to add three
zeros to get the correct value.
UTM 32 730000 5170000

Quoted message said:

The map (all in Italian) seems to imply it covers UTM zone ('Fuso'😉
32.

the 12° meridian is between UTM zone 32 and zone 33. All positions west
of 12° are correct with zone 32, but all positions east of 12° are
printed wrong.

Quoted message said:

Or the actual co-ords of a particular location, say the centre of Arabba.

UTM 32 720720 5153333

hth
Anton

In article <[email hidden]>, Terry Pinnell

Quoted message said:

The Italian map I have bought for our walking holiday in the Dolomites
(tomorrow) is called 'Carta Topografica',1:25,000, #7 'Alta Badia -
Arabba - Mamolada'. It's marked with occasional degs/mins but the main
grid appears to be in UTM. Trouble is, I'm darned if I can interpret
them!

Unless the map you have specifically mentions WGS 84, set you GPS's map
DATUM to European 1950 (NOT 1979) - you might see an abbreviation like
EUR-I or EUR-J somewhere on your map. The display format should be set to
UTM of course.

Have a great time.

ron

(Ron Wong) said:

In article <[email hidden]>, Terry Pinnell

Quoted message said:

The Italian map I have bought for our walking holiday in the Dolomites
(tomorrow) is called 'Carta Topografica',1:25,000, #7 'Alta Badia -
Arabba - Mamolada'. It's marked with occasional degs/mins but the main
grid appears to be in UTM. Trouble is, I'm darned if I can interpret
them!

Unless the map you have specifically mentions WGS 84, set you GPS's map
DATUM to European 1950 (NOT 1979) - you might see an abbreviation like
EUR-I or EUR-J somewhere on your map. The display format should be set to
UTM of course.

Have a great time.

ron

Many thanks, Ron - appreciate the advice.

--
Terry, West Sussex, UK

Keith Sheppard said:

Terry

I have been through this one. It took me ages to suss it out. Italian maps
use Gauss Boaga datum and a central meridian which runs through Monte Mario,
an observatory near Rome. That's some obscure distance west of Greenwich
(12 degrees, 27 minutes and 8.4 seconds).

I don't believe that the grid you see is actually UTM. It's Italian
standard grid. The Italians divide their country into two zones East and
West of the meridian and I think the grid is relative to this.

After many weeks of frustration I finally invented a whole new MapMan
feature just to deal with Italian maps - which I called "Grid Systems". In
fact, if you download MapMan and look at the Help text for "Grid Systems"
you will find that it starts with a discussion of Italian walking maps.

MapMan's Grid System isn't essential for calibrating an Italian map but I
found it made the job easier. If you are using a different mapping
application then I would ignore the grid lines altogether and calibrate the
map using the degrees marked along the edges (but remembering to use Gauss
Boaga datum).

My attempts to calibrate my own Italian map were only moderately successful.
When I finally got to Italy I found that all my map items were about 200
feet out but as the error was constant and always in the same direction I
was soon able to mentally compensate. It would have been better if I'd
taken the computer with me to make the necessary adjustments "in the field"
but my other half usually vetoes taking laptops on holiday!

Regards
Keith

Keith: Happily, looks like it was UTM after all! From Anton's reply I
was able to calibrate two of the 9 sections in time. Thanks again,
Anton. Now closing down for a fortnight.

--
Terry, West Sussex, UK