Question about Gauss-Kruger projection

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lky
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Question about Gauss-Kruger projection

lky
Hello, everyone

I'm a new learner of gdal that I find that gdal open source can't support the Gauss-Kruger projection.Some friends tell me that I can use UTM(Universal Transverse Mercator) to replace the Gauss-Kruger. But I am not sure of this.

My questions are

1.How to use Gauss-Kruger projection by gdal open source?

2.Can the UTM project replace Gauss-Kruger projection? If it can, which is the difference between them and which I should pay attention to in program?

Thanks a lot.

yours
Kunyang Li        

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Re: Question about Gauss-Kruger projection

Frank Warmerdam
On 10/27/05, lky <[hidden email]> wrote:
> Hello, everyone
>
> I'm a new learner of gdal that I find that gdal open source can't support the Gauss-Kruger projection.Some friends tell me that I can use UTM(Universal Transverse Mercator) to replace the Gauss-Kruger. But I am not sure of this.
>
> My questions are
>
> 1.How to use Gauss-Kruger projection by gdal open source?

Kunyang Li,

My understanding is that Gauss-Kruger is another name for
Transverse Mercator.   GDAL (and PROJ.4, etc) supports
Transverse Mercator just fine.

> 2.Can the UTM project replace Gauss-Kruger projection? If it can, which is the difference between them and which I should pay attention to in program?

UTM is a specialized transverse mercator.  That is, UTM "zones"
are essentially aliases for transverse mercator with particular
projection parameters.  The central meridian varies by zone.

I believe it would be safer to say you can use Transverse Mercator
for Gauss-Kruger.  Some Gauss-Kruger projections are zonal, and
*might* happen to match up exactly with UTM zones, but this is
by no means certain.   So pay close attention to the parameters
(central meridian, center latitude, scale, false easting and false northing).

Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, [hidden email]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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AW: Question about Gauss-Kruger projection

Uwe Schmitz-2
In reply to this post by lky
Kunyang Li,

>
> Hello, everyone
>
> I'm a new learner of gdal that I find that gdal open source
> can't support the Gauss-Kruger projection.Some friends tell
> me that I can use UTM(Universal Transverse Mercator) to
> replace the Gauss-Kruger. But I am not sure of this.
>
> My questions are
>
> 1.How to use Gauss-Kruger projection by gdal open source?
>
I don't know what you want to do, but this
is an example, how to warp a GeoTiff-File
between two Gauss-Krueger-Systems:

$ gdalinfo G33945698.tif
Driver: GTiff/GeoTIFF
Size is 4000, 4000
Coordinate System is:
PROJCS["DHDN / Gauss-Kruger zone 3",
    GEOGCS["DHDN",
        DATUM["Deutsches_Hauptdreiecksnetz",
            SPHEROID["Bessel 1841",6377397.155,299.1528128000008,
                AUTHORITY["EPSG","7004"]],
            AUTHORITY["EPSG","6314"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4314"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",9],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",3500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","31493"]]
Origin = (3394000.000000,5700000.000000)
Pixel Size = (0.50000000,-0.50000000)
<snip ...>

$ gdalwarp -tr 0.5 0.5 -t_srs EPSG:31466 G33945698.tif tr.tif
Creating output file that is 4160P x 4160L.
:0...10...20...30...40...50...60...70...80...90...100 - done.

$ gdalinfo tr.tif
Driver: GTiff/GeoTIFF
Size is 4160, 4160
Coordinate System is:
PROJCS["DHDN / Gauss-Kruger zone 2",
    GEOGCS["DHDN",
        DATUM["Deutsches_Hauptdreiecksnetz",
            SPHEROID["Bessel 1841",6377397.155,299.1528128000008,
                AUTHORITY["EPSG","7004"]],
            AUTHORITY["EPSG","6314"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4314"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",6],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",2500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","31466"]]
Origin = (2602627.814926,5700012.818412)
Pixel Size = (0.50000000,-0.50000000)
<snip ...>


> 2.Can the UTM project replace Gauss-Kruger projection? If it
> can, which is the difference between them and which I should
> pay attention to in program?
>
UTM and Gauss-Krueger based (matematically) on the same
approach. Only some parameters (zone width, scale factor
for central meridian, ...) are different.

Hope that helps
uwe
---------------------------------------------------------
... Uwe Schmitz  Landesvermessungsamt Nordrhein-Westfalen
... Muffendorfer Str. 19 - 21              D - 53177 Bonn
... E-mail:       [hidden email]
... Internet:     http://www.lverma.nrw.de
 

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