AW: [Gdal-dev] Question about Gauss-Kruger projection

[uwe.schmitz at lverma.nrw.de]

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:       uwe.schmitzNO at SPAMlverma.nrw.de
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