Projection

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Projection

macho
Hi List!

I gotta small problem here to proof that qgis is prime-time ready but ..
i have a raster and 3 vektor layers that i want to overlay
Rasterlayer is a geoTIF and as of .prj file:
PROJCS["UTM_WGS84_M15",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000],PARAMETER["False_Northing",-5000000],PARAMETER["Central_Meridian",15],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0],UNIT["Meter",1]]

therefore a UTM_WGS84_M15 which seems to be not in the list of
projections (or am i wrong?)

the Vektorlayers are normal shape files and as of .prj file:
PROJCS["MGI_Austria_GK_M34",GEOGCS["GCS_MGI",DATUM["D_MGI",SPHEROID["Bessel_1841",6377397.155,299.1528128]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",750000.0],PARAMETER["False_Northing",-5000000.0],PARAMETER["Central_Meridian",16.33333333333334],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]

which i expect to be the MGI / Austria M34 projection and i can find it
in the KBS List


So can anybody give me a hint howto solve the rasterlayer projection
because otherwise i cant overlay vector OTF on the Raster (My
Information is that it can only work in that direction.

Thanks a lot
regards
Werner
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Re: Projection

Otto Dassau
Hi Werner,

I tried to find your raster file projection "UTM_WGS84_M15", but it doesn't seem
to be available. What happens if you create your own CRS in QGIS. From your .prj
file this should work:

Setings -> Custom CRS

Name: UTM_WGS84_M15
Parameters: +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9996 +x_0=500000 +y_0=-5000000
+ellps=WGS84 +units=m +datum=WGS84 +no_defs

Then you load the raster, which is projected in "UTM_WGS84_M15", choose your
custom projection in the Project Properties dialog, select "Enable OTF" and
load the shape. The vector should now fit with the raster.

 regards,
  Otto

On Mon, 05 Jan 2009 09:30:20 +0100
Werner Macho <[hidden email]> wrote:

> Hi List!
>
> I gotta small problem here to proof that qgis is prime-time ready but ..
> i have a raster and 3 vektor layers that i want to overlay
> Rasterlayer is a geoTIF and as of .prj file:
>
PROJCS["UTM_WGS84_M15",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1
984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519
943295]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000],PA
RAMETER["False_Northing",-5000000],PARAMETER["Central_Meridian",15],PARAMETER["
Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0],UNIT["Meter",1]]
>
> therefore a UTM_WGS84_M15 which seems to be not in the list of
> projections (or am i wrong?)
>
> the Vektorlayers are normal shape files and as of .prj file:
>
PROJCS["MGI_Austria_GK_M34",GEOGCS["GCS_MGI",DATUM["D_MGI",SPHEROID["Bessel_184
1",6377397.155,299.1528128]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925
199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",750000.0],
PARAMETER["False_Northing",-5000000.0],PARAMETER["Central_Meridian",16.33333333
333334],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT[
"Meter",1.0]]

>
> which i expect to be the MGI / Austria M34 projection and i can find it
> in the KBS List
>
>
> So can anybody give me a hint howto solve the rasterlayer projection
> because otherwise i cant overlay vector OTF on the Raster (My
> Information is that it can only work in that direction.
>
> Thanks a lot
> regards
> Werner
> _______________________________________________
> Qgis-user mailing list
> [hidden email]
> http://lists.osgeo.org/mailman/listinfo/qgis-user
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Re: Projection

macho
Hi Otto! (and list)

Thanks for your help. It worked.
At least in Windows - because i can remember that i tried nearly the
same with Linux and it did not.
But I have to check that anyway when I'm back home and on my Linux-PC.
Expect a mail with a report on linux too ;)

So it seems that there is really no existing projection for the (in
austria) common UTM WGS84 M15.
And nevertheless - all files i loaded into QGIS where fully equipped
with a .prj file.
So were there any discussion about reading .prj files i missed or can
someone (hopefully a developer) provide me some information why QGIS is
not reading .prj infos?
At least a small button with "read prj file" to give the right .prj file
for reading raster or vector files would even be more helpfull (and at
least easier) than defining the projection by myself.
I know it's the same as SPSS vs. R where it can lead to wrong
interpreted results using a click-click interface compared to a
"console-driven" text interface where you really have to know what you
are doing but .. see the .prj files are provided so why looking for the
projection if it is already there?

Is there any ongoing discussion about trying to read the .prj files
automatically or at least integrate them in the loading process somehow?

thanks to all for your help and information

regards
werner

> Hi Werner,
>
> I tried to find your raster file projection "UTM_WGS84_M15", but it doesn't seem
> to be available. What happens if you create your own CRS in QGIS. From your .prj
> file this should work:
>
> Setings -> Custom CRS
>
> Name: UTM_WGS84_M15
> Parameters: +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9996 +x_0=500000 +y_0=-5000000
> +ellps=WGS84 +units=m +datum=WGS84 +no_defs
>
> Then you load the raster, which is projected in "UTM_WGS84_M15", choose your
> custom projection in the Project Properties dialog, select "Enable OTF" and
> load the shape. The vector should now fit with the raster.
>  

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Re: Projection

Albin Blaschka-4
Werner Macho schrieb:
[...]
> So were there any discussion about reading .prj files i missed or can
> someone (hopefully a developer) provide me some information why QGIS is
> not reading .prj infos?
> At least a small button with "read prj file" to give the right .prj file
> for reading raster or vector files would even be more helpfull (and at
> least easier) than defining the projection by myself.
[...]

Hello,

I am no developer, but I once had the problem with a .prj - File on
Linux that ist was there, but not readable: don't ask me why - IIRC it
was because of some weird copying back and forth - and I was not the
owner of the file... So I had no rights to read the file...

A second possibility would be that the .prj File is corrupted, but then
it should not work on windows either...or maybe different coding of line
-endings (CR/LF... but I do not know if this could be an issue with a
.prj-file...)

Good Luck!

Albin


--
| Albin Blaschka, Mag.rer.nat.
| Etrichstrasse 26, A-5020 Salzburg
| * www.albinblaschka.info * www.thinkanimal.info *
| - It's hard to live in the mountains, hard but not hopeless!
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Re: Projection

Helmut Kudrnovsky
In reply to this post by macho
hi,

be carefull about on-the-fly-projection with wgs84-data and austrian data (MGI) because there are a few different towgs-informations in the epsg-database.

so if the towgs-information is not considered, there can be a north-east shift of about 75m during the on-the-fly-projection.

i prepared some information about this issue under

http://www.alectoria.at/content/view/17/1/

also i prepared there some prj-files including the towgs-information for Austria.

best regards
helli

-------------------------------------
  helmut kudrnovsky
  www.alectoria.at


------------------------------

Message: 3
Date: Wed, 7 Jan 2009 09:05:46 +0100
From: Otto Dassau <[hidden email]>
Subject: Re: [Qgis-user] Projection
To: [hidden email]
Message-ID: <20090107090546.12b1c76a@nature>
Content-Type: text/plain; charset=US-ASCII

Hi Werner,

I tried to find your raster file projection "UTM_WGS84_M15", but it doesn't seem
to be available. What happens if you create your own CRS in QGIS. From your .prj
file this should work:

Setings -> Custom CRS

Name: UTM_WGS84_M15
Parameters: +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9996 +x_0=500000 +y_0=-5000000
+ellps=WGS84 +units=m +datum=WGS84 +no_defs

Then you load the raster, which is projected in "UTM_WGS84_M15", choose your
custom projection in the Project Properties dialog, select "Enable OTF" and
load the shape. The vector should now fit with the raster.

 regards,
  Otto

On Mon, 05 Jan 2009 09:30:20 +0100
Werner Macho <[hidden email]> wrote:

> Hi List!
>
> I gotta small problem here to proof that qgis is prime-time ready but ..
> i have a raster and 3 vektor layers that i want to overlay
> Rasterlayer is a geoTIF and as of .prj file:
>
PROJCS["UTM_WGS84_M15",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1
984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519
943295]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000],PA
RAMETER["False_Northing",-5000000],PARAMETER["Central_Meridian",15],PARAMETER["
Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0],UNIT["Meter",1]]
>
> therefore a UTM_WGS84_M15 which seems to be not in the list of
> projections (or am i wrong?)
>
> the Vektorlayers are normal shape files and as of .prj file:
>
PROJCS["MGI_Austria_GK_M34",GEOGCS["GCS_MGI",DATUM["D_MGI",SPHEROID["Bessel_184
1",6377397.155,299.1528128]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925
199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",750000.0],
PARAMETER["False_Northing",-5000000.0],PARAMETER["Central_Meridian",16.33333333
333334],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT[
"Meter",1.0]]

>
> which i expect to be the MGI / Austria M34 projection and i can find it
> in the KBS List
>
>
> So can anybody give me a hint howto solve the rasterlayer projection
> because otherwise i cant overlay vector OTF on the Raster (My
> Information is that it can only work in that direction.
>
> Thanks a lot
> regards
> Werner
> _______________________________________________
> Qgis-user mailing list
> [hidden email]
> http://lists.osgeo.org/mailman/listinfo/qgis-user


------------------------------

Message: 4
Date: Wed, 07 Jan 2009 11:34:35 +0100
From: Werner Macho <[hidden email]>
Subject: Re: [Qgis-user] Projection
To: Otto Dassau <[hidden email]>
Cc: [hidden email]
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Otto! (and list)

Thanks for your help. It worked.
At least in Windows - because i can remember that i tried nearly the
same with Linux and it did not.
But I have to check that anyway when I'm back home and on my Linux-PC.
Expect a mail with a report on linux too ;)

So it seems that there is really no existing projection for the (in
austria) common UTM WGS84 M15.
And nevertheless - all files i loaded into QGIS where fully equipped
with a .prj file.
So were there any discussion about reading .prj files i missed or can
someone (hopefully a developer) provide me some information why QGIS is
not reading .prj infos?
At least a small button with "read prj file" to give the right .prj file
for reading raster or vector files would even be more helpfull (and at
least easier) than defining the projection by myself.
I know it's the same as SPSS vs. R where it can lead to wrong
interpreted results using a click-click interface compared to a
"console-driven" text interface where you really have to know what you
are doing but .. see the .prj files are provided so why looking for the
projection if it is already there?

Is there any ongoing discussion about trying to read the .prj files
automatically or at least integrate them in the loading process somehow?

thanks to all for your help and information

regards
werner

> Hi Werner,
>
> I tried to find your raster file projection "UTM_WGS84_M15", but it doesn't seem
> to be available. What happens if you create your own CRS in QGIS. From your .prj
> file this should work:
>
> Setings -> Custom CRS
>
> Name: UTM_WGS84_M15
> Parameters: +proj=tmerc +lat_0=0 +lon_0=15 +k=0.9996 +x_0=500000 +y_0=-5000000
> +ellps=WGS84 +units=m +datum=WGS84 +no_defs
>
> Then you load the raster, which is projected in "UTM_WGS84_M15", choose your
> custom projection in the Project Properties dialog, select "Enable OTF" and
> load the shape. The vector should now fit with the raster.
>  
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best regards
Helmut
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Re: Projection

pcav
Helmut Kudrnovsky ha scritto:

> be carefull about on-the-fly-projection with wgs84-data and austrian data (MGI) because there are a few different towgs-informations in the epsg-database.
>
> so if the towgs-information is not considered, there can be a north-east shift of about 75m during the on-the-fly-projection.

same for Italy (Gauss-Boaga). Actually this is a serious problem for
professional use, and should be solved.
All the best.
pc
--
Paolo Cavallini, see: * http://www.faunalia.it/pc *
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