[GRASS-dev] r.proj from GaussBoaga to UTM

Christian_Tiso1 · February 25, 2009, 4:02pm

Hi,
using command r.proj to reproject a raster topographic map from a Gauss Boaga location (EPSG:3003) to a UTM location (EPSG:32632) I obtain a shift error of the reprojected map of about 40-50m in south direction. It is related to the towgs84 bursa wolf parameters?
Is this a known bug?
I’m using Grass 6.3.0-2 on a Mac Intel with Moretti’s Build binaries.

Thank you

Christian

Christian Tiso, collaborator

Department of Civil and Environmental Engineering
University of Trento
via Mesiano 77, I-38050 Trento, ITALY
[http://www.ing.unitn.it/dica](http://www.ing.unitn.it/dica)
phone: +39 0461 882610
fax: +39 0461 882672
E-mail: [christian.tiso@ing.unitn.it](mailto:christian.tiso@ing.unitn.it)

neteler · February 25, 2009, 11:19pm

On Wed, Feb 25, 2009 at 5:02 PM, Christian Tiso
<christian.tiso@ing.unitn.it> wrote:

Hi,
using command r.proj to reproject a raster topographic map from a Gauss
Boaga location (EPSG:3003) to a UTM location (EPSG:32632) I obtain a shift
error of the reprojected map of about 40-50m in south direction. It is
related to the towgs84 bursa wolf parameters?
Is this a known bug?
I'm using Grass 6.3.0-2 on a Mac Intel with Moretti's Build binaries.

please post

g.proj -w

I assume that the datum definition is lacking or wrong (towgs84).

Markus

Christian_Tiso1 · February 26, 2009, 7:56am

Thank you markus, you’re right, there’s no datum definition:

GRASS 6.3.0 (fassaGB):~ > g.proj -w
PROJCS[“Transverse Mercator”,
GEOGCS[“international”,
DATUM[“unknown”,
SPHEROID[“International_1924”,6378388,297]],
PRIMEM[“Greenwich”,0],
UNIT[“degree”,0.0174532925199433]],
PROJECTION[“Transverse_Mercator”],
PARAMETER[“latitude_of_origin”,0],
PARAMETER[“central_meridian”,9],
PARAMETER[“scale_factor”,0.9996],
PARAMETER[“false_easting”,1500000],
PARAMETER[“false_northing”,0],
UNIT[“Meter”,1]]

but this is beacause I created a new location from the GUI start panel of GRASS by choosing the “EPSG code” button and selectiong the 3003 code which should be the one related to the GaussBoaga, Rome 1940 Monte Mario projections.

Where am I wrong? It is not possible to create such a new location only by choosing the EPSG code?

Thank you for helping me.

Christian Tiso

Il giorno 26/feb/09, alle ore 00:19, Markus Neteler ha scritto:

On Wed, Feb 25, 2009 at 5:02 PM, Christian Tiso
<christian.tiso@ing.unitn.it> wrote:

Hi,

using command r.proj to reproject a raster topographic map from a Gauss

Boaga location (EPSG:3003) to a UTM location (EPSG:32632) I obtain a shift

error of the reprojected map of about 40-50m in south direction. It is

related to the towgs84 bursa wolf parameters?

Is this a known bug?

I’m using Grass 6.3.0-2 on a Mac Intel with Moretti’s Build binaries.

please post

g.proj -w

I assume that the datum definition is lacking or wrong (towgs84).

Markus

Christian Tiso, collaborator

Department of Civil and Environmental Engineering
University of Trento
via Mesiano 77, I-38050 Trento, ITALY
[http://www.ing.unitn.it/dica](http://www.ing.unitn.it/dica)
phone: +39 0461 882610
fax: +39 0461 882672
E-mail: [christian.tiso@ing.unitn.it](mailto:christian.tiso@ing.unitn.it)

Hamish · February 27, 2009, 2:29am

Christian Tiso wrote:

Thank you markus, you're right, there's no datum
definition:

GRASS 6.3.0 (fassaGB):~ > g.proj -w
PROJCS["Transverse Mercator",
    GEOGCS["international",
        DATUM["unknown",

SPHEROID["International_1924",6378388,297]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433]],

....

but this is beacause I created a new location from the GUI
start panel of GRASS by choosing the "EPSG code"
button and selectiong the 3003 code which should be the one
related to the GaussBoaga, Rome 1940 Monte Mario
projections.

Where am I wrong? It is not possible to create such a new
location only by choosing the EPSG code?

The /usr/share/proj/epsg file's version of 3003 only defines the 1924
International ellipsoid, not the datum. so that's all grass knows about:

# Monte Mario / Italy zone 1
<3003> +proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +ellps=intl +units=m +no_defs <>

try http://www.epsg-registry.org/ & go to "retrieve by code".

is "Monte Mario" aka "Rome 1940" datum? if so the epsg file may be faulty.
(don't know; ask on the proj4 mailing list)

grass's datum table has rome40:

# Rome 1940 (Sardinia Parameters)
rome40 "Monte_Mario" international dx=-225 dy=-65 dz=9

so you could run g.setproj in the PERMANENT mapset, choosing only to
change the datum and set it that way, or hack the PROJ_INFO file manually.

Hamish

Christian_Tiso1 · February 27, 2009, 7:36am

Tahnk you Hamish,
running g.setproj in the PERMANENT mapset worked fine.

Thank you all for helping

Christian

Il giorno 27/feb/09, alle ore 03:29, Hamish ha scritto:

Christian Tiso wrote:

Thank you markus, you’re right, there’s no datum

definition:

GRASS 6.3.0 (fassaGB):~ > g.proj -w

PROJCS[“Transverse Mercator”,

GEOGCS[“international”,

DATUM[“unknown”,

SPHEROID[“International_1924”,6378388,297]],

PRIMEM[“Greenwich”,0],

UNIT[“degree”,0.0174532925199433]],

…

but this is beacause I created a new location from the GUI

start panel of GRASS by choosing the “EPSG code”

button and selectiong the 3003 code which should be the one

related to the GaussBoaga, Rome 1940 Monte Mario

projections.

Where am I wrong? It is not possible to create such a new

location only by choosing the EPSG code?

The /usr/share/proj/epsg file’s version of 3003 only defines the 1924
International ellipsoid, not the datum. so that’s all grass knows about:

Monte Mario / Italy zone 1

<3003> +proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +ellps=intl +units=m +no_defs <>

try http://www.epsg-registry.org/ & go to “retrieve by code”.

is “Monte Mario” aka “Rome 1940” datum? if so the epsg file may be faulty.
(don’t know; ask on the proj4 mailing list)

grass’s datum table has rome40:

Rome 1940 (Sardinia Parameters)

rome40 “Monte_Mario” international dx=-225 dy=-65 dz=9

so you could run g.setproj in the PERMANENT mapset, choosing only to
change the datum and set it that way, or hack the PROJ_INFO file manually.

Hamish

Christian Tiso, collaborator

Department of Civil and Environmental Engineering
University of Trento
via Mesiano 77, I-38050 Trento, ITALY
[http://www.ing.unitn.it/dica](http://www.ing.unitn.it/dica)
phone: +39 0461 882610
fax: +39 0461 882672
E-mail: [christian.tiso@ing.unitn.it](mailto:christian.tiso@ing.unitn.it)

neteler · March 1, 2009, 7:24pm

On Thu, Feb 26, 2009 at 8:56 AM, Christian Tiso
<christian.tiso@ing.unitn.it> wrote:

Thank you markus, you're right, there's no datum definition:
GRASS 6.3.0 (fassaGB):~ > g.proj -w
PROJCS["Transverse Mercator",
GEOGCS["international",
DATUM["unknown",
SPHEROID["International_1924",6378388,297]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",9],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",1500000],
PARAMETER["false_northing",0],
UNIT["Meter",1]]
but this is beacause I created a new location from the GUI start panel of
GRASS by choosing the "EPSG code" button and selectiong the 3003 code which
should be the one related to the GaussBoaga, Rome 1940 Monte Mario
projections.
Where am I wrong? It is not possible to create such a new location only by
choosing the EPSG code?
Thank you for helping me.

In GRASS 6.4 you are additionally asked for a datum selection.
I thought it was there also for 6.3...

Martin fixed it for wxPython 2 days ago, so also the LocationWizard
supports this.

Markus