R: [Proj] cs2cs usage

[marco.pasetti at alice.it]

Hi Andrea,
 
>I'm not sure about that. How do you execute it?
 
from Windows terminal (cmd.exe)
 
>I guess they are very needed. Did you try to add  +towgs84=<your
>commaseparated values>?
 
I tried with:
 
cs2cs -v +init=epsg:4326 +to +init=epsg:3003 +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
 
reporting:
 
# ---- From Coordinate System ----
#Lat/long (Geodetic alias)
#
# +init=epsg:4326 +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs
# +towgs84=0,0,0
#--- following specified but NOT used
# +ellps=WGS84
# ---- To Coordinate System ----
#Transverse Mercator
#       Cyl, Sph&Ell
# +init=epsg:3003 +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
# +proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +ellps=intl
# +units=m +no_defs
 
then I entered the WGS84 point: 10°44'09,70E 45°45'12.00N as
 
10.73602778 45.75333333
 
I simply transformed x°y'z'' to D [° decimal format] using D = (x + y/60 + z/3600); is it correct?
 
BTW, I had the following result:
 
1635050.62      5068127.39 -45.30
 
now further questions:
 
1) what does "-45.30" mean?
 
2) I roughly checked the point on my GRASS-imported rasters (imported in the location created by GRASS using EPSG code 3003 and the previously mentioned towgs84 parameters), and it seems to "be" where I expected... but I cannot be sure! I know the region, and I *have* some conspicuous points to *use* (it's on lake garda, and there's a peak nearby the point of interest that is clearly visible from the raster map), but this procedure is fairly long to be called a *secure and precise check procedure* (that's why I used the word *roughly*)
 
Many thanks for your help
 
Marco
 
PS: buona Pasqua ;-)

________________________________

Da: proj-bounces at lists.maptools.org per conto di andrea antonello
Inviato: gio 20/03/2008 14.33
A: PROJ.4 and general Projections Discussions
Oggetto: Re: [Proj] cs2cs usage



> I read cs2cs manual page, but I still have big doubts about it! quickly:
>
> 0. Preamble: I built PROJ.4 4.6 on windows using MinGW
>
> 1. Question 1: when I launch cs2cs from command line it executes the
> requested operation and then waits for others inputs... how can I quit,
> without the need of killing the process in task manager?

I'm not sure about that. How do you execute it?

> 2. Question 2: I need to trasform single points from WGS84 (EPSG ID = 4326)
> to Gauss-Boaga Roma40 West (EPSG ID = 3003)
> while ID=4326 determinates an univocal datum, to correctly define
> Gauss-Boaga Roma40 West I need to specify also +towgs84 parameters,
> retrieved by GRASS (creating a new location in GRASS using 3003 EPSG code,
> it asks for furthers options, suggesting the correct parameters to set):
> the complete datum definition for Gauss-Boaga Roma40 West is as follows
> (from GRASS):
>
> EPSG ID = 3003
> Option 2
> Used in Italy (Peninsular Part)
> towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
> Accuracy 3-4m
>
> how can I use cs2cs respecting the previous parameters?
> I tried with cs2cs +init=epsg:4326 +to +init=epsg:3003
> but I don't know how to set towgs84 parameters (and even if they are needed)

I guess they are very needed. Did you try to add  +towgs84=<your
commaseparated values> ?

Ciao
Andrea


> Thanks fo help
>
> Marco
>
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>  Proj mailing list
>  Proj at lists.maptools.org
>  http://lists.maptools.org/mailman/listinfo/proj
>
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