[OSRS-PROJ] Projection parameters for Italian old IGM?

[Bud P. Bruegger]

Hi Gerald,

again thanks for the help.  I made a mistake in the coordinates that I
wrote, adding a 1 in front since I thought it was a typo.   Sorry for
that.   So I try to be more precise on this.  (Now installing proj on
my machine...).

So the coordinates that I would like to have are:  (long is west of
Rome-M.Mario of 12d 27' 8.4")

1d07'30"  43d00'00"           >>>    689760.45     4763707.54
1d07'30"  42d55'00"           >>>    690021.52     4754462.74
1d00'00"  42d55'00"           >>>    700210.22     4754751.94
1d00'00"  43d00'00"           >>>    699948.89     4763999.07

So trying the last two points in Greenwich long run through
proj +proj=utm +zone=32 +ellps=intl:

11d27'8.4" 42d55'00"           
yields                    700169.30     4754564.18
but should be about       700210.22     4754751.94

11d27'8.4" 43d00'00"            
yields                    699899.19     4763819.04
but should be aobut       699948.89     4763999.07

You see that the numbers are in the UTM range.  The map quite clearly
states that the grid is UTM 32 on the intnl. ellipsoid, so there
shouldn't be any doubt there.  And also the lat/long refers to the
same ellipsoid.  The projection talks about the European Datum of
1950--no information what datum is used for the lat/long....

Could there be a datum shift to consider???  Any clue where I'm going
wrong?

Again, many thanks for your help.

--b


On 29 Apr 2003 14:52:35 -0400
"Gerald I. Evenden" <gerald.evenden at verizon.net> wrote:

> I am going to skip down to what I think is the core of the problem
> 
> Neither of the following eastings and northings are UTM values
> which at the equator the easting stays in the range of 110,000
> to 890,000 meters (+-3.5d from CM).  Less as one heads north.
> 
> I suspect that you are dealing with coordinates from Italian
> Gauss-Boaga zones that do have false eastings in the 1,500,000 meter
> range.
> 
> I tried the following script for "zone 1":
> 
> ./lproj +proj=tmerc +ellps=intl +lon_0=9e +k_0=.9996 +x_0=1500000 <<EOF
> 11d19'38.4E 43N
> EOF
> 
> and got the following answer:
> 
> 1689709.55      4763529.01
> 
> Looks a lot like your second set of numbers after rounding, eh?
> 
> On Tue, 2003-04-29 at 13:05, Bud P.Bruegger wrote:
> 	... 
> > Here the values that I expect:
> > 
> > for 1d 07' 30" west of the Rome Meridian (12d27'08".04) and 43d 0' 0"
> > 
> > the UTM coordinates should roughly be (read from a georeferenced
> > raster map) 
> > 
> > E=1689760.45  
> > N=4763707.54
> > 
> > Note that this is different from Gauss-Boaga.  The map actually prints
> > the Gauss-Boaga coordinates of that corner that are:
> > 
> > E=1689710
> > N=4763529
> > 
> > so some 200 meters off
> > 
> > I hope this defines the problem better.  Again, many thanks for your
> > help!
> > 
> > --b
> 
> 
> 


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| Bud P. Bruegger, Ph.D. 
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