Hi,
I'm interesting about coordinate transformation from Monte Mario /Italy2
(3004) to UTM-WGS84 (32633); the first transformation was made without the 7
parameters of Bursa Wolf and I obteined an error of 160m on northing
coordinate and 12m on easting coordinate.
in this case, what are the transformation parameters? when aren't the
parameters, its are 0?
a II transformation has been effettued insertin in the native .prj the
TOWGS84 string with 7 local parameters of Borsa Wolf, in the order TX, TY,
TZ, RX, RY, RZ, Kand reprojecting in 32633 srs.
in this way i obteined un error of 11m on easting coordinate and 1.97m on
northing coordinate.
I'm trying to modify the .prj to obtain one best approssimation but
Geoserver don't see the new parameters and my GML in WFS request has even
the same points.
why Geoserver don't see new parameters? What is the right procedure to
adjust my transformation?
thank's for help. M.MI
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Hi,
You are not seeing the change mostly likely because GEoServer is using its internal representation of 3004, and not the native .prj file. When you set up your feature type there are three options in the "SRS Handling" field:
1. Force declared SRS (native will be ignored): this is the default, and is my guess as to what is happening.
2. Reproject from native to declared SRS
3. Leave the native SRS unaltered
I think what you probably want is option 3.
Anyways, that is my best guess. Let us know how your feature type is configured and we can help you further.
-Justin
mariaMI wrote:
Hi,
I'm interesting about coordinate transformation from Monte Mario /Italy2
(3004) to UTM-WGS84 (32633); the first transformation was made without the 7
parameters of Bursa Wolf and I obteined an error of 160m on northing
coordinate and 12m on easting coordinate.
in this case, what are the transformation parameters? when aren't the
parameters, its are 0?
a II transformation has been effettued insertin in the native .prj the
TOWGS84 string with 7 local parameters of Borsa Wolf, in the order TX, TY,
TZ, RX, RY, RZ, Kand reprojecting in 32633 srs.
in this way i obteined un error of 11m on easting coordinate and 1.97m on
northing coordinate.
I'm trying to modify the .prj to obtain one best approssimation but
Geoserver don't see the new parameters and my GML in WFS request has even
the same points.
why Geoserver don't see new parameters? What is the right procedure to
adjust my transformation?
thank's for help. M.MI
--
Justin Deoliveira
The Open Planning Project
jdeolive@anonymised.com
mariaMI ha scritto:
Hi,
I'm interesting about coordinate transformation from Monte Mario /Italy2
(3004) to UTM-WGS84 (32633); the first transformation was made without the 7
parameters of Bursa Wolf and I obteined an error of 160m on northing
coordinate and 12m on easting coordinate.
in this case, what are the transformation parameters? when aren't the
parameters, its are 0?
a II transformation has been effettued insertin in the native .prj the
TOWGS84 string with 7 local parameters of Borsa Wolf, in the order TX, TY,
TZ, RX, RY, RZ, Kand reprojecting in 32633 srs.
in this way i obteined un error of 11m on easting coordinate and 1.97m on
northing coordinate.
I'm trying to modify the .prj to obtain one best approssimation but
Geoserver don't see the new parameters and my GML in WFS request has even
the same points.
why Geoserver don't see new parameters? What is the right procedure to
adjust my transformation?
thank's for help. M.MI
Elaborating a little more on Justin's answer you either:
a) modify the .prj directly with your custom towgs84 parameters
and use "leave" as the srs handling
b) create a new custom epsg code in epsg.properties with the custom
parameters, and then declare the custom epsg code as the srs
of your feature type and set "force" to override the .prj
Yet, from what you say it seems you already got improvements in your
projection accuracy, so it seems you already did either a) or b)?
The three standard towgs84 parameters should be:
rome40 "towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68" "Italy (Peninsular Part)" "Accuracy 3-4m"
rome40 "towgs84=-168.6,-34.0,-34.0,-0.374,-0.679,-1.379,-9.48" "Italy (Sardinia)" "Accuracy 3-4m"
rome40 "towgs84=-50.2,-50.4,84.8,-0.690,-2.012,0.459,-28.08" "Italy (Sicily)" "Accuracy 3-4m"
I'm a little surprised that you're getting 11 meters error...
Can you provide me with the coordinate of your benchmark points
in 3004, then in 32633, and the .prj file contents, so that I
can try the transformation on my computer?
Cheers
Andrea
prof,
thank you for the correct parameters on peninsular Italy. i obtained a
precision of 0.33m on Northing coordinate and 1.97m on easting coordinate. I
didn't see the changes by different towgs84 for a "]" not at right position.
now i want reproject my data from 3004 (Gauss Boaga) or from 32633
(UTM-WGS84) to 900913to override my file on Google Earth. can you help me
yet? thank you, M.MI
aaime wrote:
mariaMI ha scritto:
Hi,
I'm interesting about coordinate transformation from Monte Mario /Italy2
(3004) to UTM-WGS84 (32633); the first transformation was made without
the 7
parameters of Bursa Wolf and I obteined an error of 160m on northing
coordinate and 12m on easting coordinate.
in this case, what are the transformation parameters? when aren't the
parameters, its are 0?
a II transformation has been effettued insertin in the native .prj the
TOWGS84 string with 7 local parameters of Borsa Wolf, in the order TX,
TY,
TZ, RX, RY, RZ, Kand reprojecting in 32633 srs.
in this way i obteined un error of 11m on easting coordinate and 1.97m on
northing coordinate.
I'm trying to modify the .prj to obtain one best approssimation but
Geoserver don't see the new parameters and my GML in WFS request has even
the same points.
why Geoserver don't see new parameters? What is the right procedure to
adjust my transformation?
thank's for help. M.MIElaborating a little more on Justin's answer you either:
a) modify the .prj directly with your custom towgs84 parameters
and use "leave" as the srs handling
b) create a new custom epsg code in epsg.properties with the custom
parameters, and then declare the custom epsg code as the srs
of your feature type and set "force" to override the .prjYet, from what you say it seems you already got improvements in your
projection accuracy, so it seems you already did either a) or b)?The three standard towgs84 parameters should be:
rome40 "towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68" "Italy
(Peninsular Part)" "Accuracy 3-4m"
rome40 "towgs84=-168.6,-34.0,-34.0,-0.374,-0.679,-1.379,-9.48" "Italy
(Sardinia)" "Accuracy 3-4m"
rome40 "towgs84=-50.2,-50.4,84.8,-0.690,-2.012,0.459,-28.08" "Italy
(Sicily)" "Accuracy 3-4m"I'm a little surprised that you're getting 11 meters error...
Can you provide me with the coordinate of your benchmark points
in 3004, then in 32633, and the .prj file contents, so that I
can try the transformation on my computer?
Cheers
Andrea-------------------------------------------------------------------------
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mariaMI ha scritto:
prof,
thank you for the correct parameters on peninsular Italy. i obtained a
precision of 0.33m on Northing coordinate and 1.97m on easting coordinate. I
didn't see the changes by different towgs84 for a "]" not at right position.
now i want reproject my data from 3004 (Gauss Boaga) or from 32633
(UTM-WGS84) to 900913to override my file on Google Earth. can you help me
yet? thank you, M.MI
If you want to override with Google Earth just use the KML link in
the map preview, Google Earth will open with the layer overlaied
(for the record, KML data is expressed in 4326, not in 900913).
If you want to override with Google Maps then yes, you'll have to
reproject WMS to 900913, which means you have to provide a reprojected
bbox and srsName=epsg:900913 in your wms requests... but OpenLayers
can handle most of that for you, see the Google maps example in
the GeoServer demo section, you just have to change the javascript
so that instead of topp:states it uses your layer.
Hope this helps
Cheers
Andrea
to reproject to Gauss-Boaga (3004) to 32633 (UTM WGS84) i used the TOWGS84
parameters of peninsular Italy. Now, to reproject from 3004 to 23033 (UTM
ED50) the same parameters don't are correct. what are the esact parameters
for this reprojection?
thank you everybody
aaime wrote:
mariaMI ha scritto:
prof,
thank you for the correct parameters on peninsular Italy. i obtained a
precision of 0.33m on Northing coordinate and 1.97m on easting
coordinate. I
didn't see the changes by different towgs84 for a "]" not at right
position.
now i want reproject my data from 3004 (Gauss Boaga) or from 32633
(UTM-WGS84) to 900913to override my file on Google Earth. can you help me
yet? thank you, M.MIIf you want to override with Google Earth just use the KML link in
the map preview, Google Earth will open with the layer overlaied
(for the record, KML data is expressed in 4326, not in 900913).If you want to override with Google Maps then yes, you'll have to
reproject WMS to 900913, which means you have to provide a reprojected
bbox and srsName=epsg:900913 in your wms requests... but OpenLayers
can handle most of that for you, see the Google maps example in
the GeoServer demo section, you just have to change the javascript
so that instead of topp:states it uses your layer.Hope this helps
Cheers
Andrea-------------------------------------------------------------------------
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mariaMI ha scritto:
(Maria, please subscribe to this list, it's the third time I make the post pass manually, this is getting annoying)
to reproject to Gauss-Boaga (3004) to 32633 (UTM WGS84) i used the TOWGS84
parameters of peninsular Italy. Now, to reproject from 3004 to 23033 (UTM
ED50) the same parameters don't are correct. what are the esact parameters
for this reprojection?
Hum, it's happening because of the TOWGS84 params in the epsg codes your're using.
Let's take a step back. Every time you make a reprojection request two things might happen:
* datum change
* projection change
The reprojection operation is driven by the definition of the
source and destination coordinate systems.
The source coordinate system may be picked from two places:
* the data itself (in your case, the .prj file), if the srs handling
is defined as "leave" or "reproject"
* the espg code you declared, in case of "force"
The destination coordinate system is usually got from the request,
but in the case of srs handling "reproject" (reproject from native to
declared, that is), it will be picked from your declaration in the
feature type (that is, unless the request asks for another srs, in
that case you go from native to the request one directly).
Now, if the source crs is used, then the definition is picked direclty
from the .prj file, and thus the bursa wolf params of the the wkt
definition will be used.
What about the destination one? Well, no matter what, if you say
the destination one is epsg:23033, then the EPSG definition will
be used with the default TOWGS84 params, as reported by
the SRS list page, which in this case are:
PROJCS["ED50 / UTM zone 33N",
GEOGCS["ED50",
DATUM["European Datum 1950",
SPHEROID["International 1924", 6378388.0, 297.0, AUTHORITY["EPSG","7022"]],
TOWGS84[-157.89, -17.16, -78.41, 2.118, 2.697, -1.434, -1.1097046576093785],
AUTHORITY["EPSG","6230"]],
PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
UNIT["degree", 0.017453292519943295],
AXIS["Geodetic longitude", EAST],
AXIS["Geodetic latitude", NORTH],
AUTHORITY["EPSG","4230"]],
PROJECTION["Transverse Mercator", AUTHORITY["EPSG","9807"]],
PARAMETER["central_meridian", 15.0],
PARAMETER["latitude_of_origin", 0.0],
PARAMETER["scale_factor", 0.9996],
PARAMETER["false_easting", 500000.0],
PARAMETER["false_northing", 0.0],
UNIT["m", 1.0],
AXIS["Easting", EAST],
AXIS["Northing", NORTH],
AUTHORITY["EPSG","23033"]]
See the TOWGS84 params? They probably aren't good for your
location in Italy.
Unfortunately you cannot redefine how GeoServer sees EPSG:23033,
but you can define your own in epsg.properties file.
Try adding the following in epsg.properties as 1023033 (you'll
have to type it on a single line, I kept it formatted in
multiple lines for readability):
PROJCS["ED50 / UTM zone 33N",
GEOGCS["ED50",
DATUM["European Datum 1950",
SPHEROID["International 1924", 6378388.0, 297.0, AUTHORITY["EPSG","7022"]],
TOWGS84[104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68],
AUTHORITY["EPSG","6230"]],
PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
UNIT["degree", 0.017453292519943295],
AXIS["Geodetic longitude", EAST],
AXIS["Geodetic latitude", NORTH],
AUTHORITY["EPSG","4230"]],
PROJECTION["Transverse Mercator", AUTHORITY["EPSG","9807"]],
PARAMETER["central_meridian", 15.0],
PARAMETER["latitude_of_origin", 0.0],
PARAMETER["scale_factor", 0.9996],
PARAMETER["false_easting", 500000.0],
PARAMETER["false_northing", 0.0],
UNIT["m", 1.0],
AXIS["Easting", EAST],
AXIS["Northing", NORTH],
AUTHORITY["EPSG","1023033"]]
(I've taken the epsg:23033 definition and replaced the
towgs84 params with the ones suggested for the italian
peninsular part).
Once you've defined this, try using it as the target
for your reprojection.
Cheers
Andrea