[mapserver-users] reprojection

[Julien Cigar]

On 09/22/2010 08:36, Rahkonen Jukka wrote:
> Hi,
>
> For sure the original image is not in EPSG:4326. You can guess it from the coordinates, for example
>   Origin = (-8563840.575678950175643,6466755.550653258338571)
> EPSG:4326 is naturally between -90,90 and -180,180. There does read
> AUTHORITY["EPSG","4326"]] in one place of the gdalinfo report, but it is in the section that tells the datum or the projection.
>
> I am not sure what the right projection could be, but I found this projection wiht the same lookin parametrers
> from my Mapserver proj directory:
> # WGS 84 / Antarctic Polar Stereographic
> <3031>  +proj=stere +lat_0=-90 +lat_ts=-71 +lon_0=0 +k=1 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs<>
>
> If this is correct, you do not need to reproject at all because your image is already in EPSG:3031.
>
> -Jukka Rahkonen-

Thanks for the clarification, looks like I misunderstood the output of 
gdalinfo..!

Julien

>
>> -----Alkuperäinen viesti-----
>> Lähettäjä: mapserver-users-bounces at lists.osgeo.org
>> [mailto:mapserver-users-bounces at lists.osgeo.org] Puolesta Julien Cigar
>> Lähetetty: 21. syyskuuta 2010 22:09
>> Vastaanottaja: mapserver-users at lists.osgeo.org
>> Aihe: [mapserver-users] reprojection
>>
>>    Hello,
>>
>> I'm trying to re-project a RASTER layer but without success so far.
>> I have the following TIFF file:
>>
>> mage at mordor:/home/mage/gis % gdalinfo antarctica_sthn_ocean.tiff
>> Driver: GTiff/GeoTIFF
>> Files: antarctica_sthn_ocean.tiff
>> Size is 12216, 9094
>> Coordinate System is:
>> PROJCS[" Projection Name = WGS_1984_Stereographic_South_Pole Units =
>> meters GeoTIFF Units = meters",
>>       GEOGCS["WGS 84",
>>           DATUM["WGS_1984",
>>               SPHEROID["WGS 84",6378137,298.257223563,
>>                   AUTHORITY["EPSG","7030"]],
>>               AUTHORITY["EPSG","6326"]],
>>           PRIMEM["Greenwich",0],
>>           UNIT["degree",0.0174532925199433],
>>           AUTHORITY["EPSG","4326"]],
>>       PROJECTION["Polar_Stereographic"],
>>       PARAMETER["latitude_of_origin",-71],
>>       PARAMETER["central_meridian",0],
>>       PARAMETER["scale_factor",1],
>>       PARAMETER["false_easting",0],
>>       PARAMETER["false_northing",0],
>>       UNIT["metre",1,
>>           AUTHORITY["EPSG","9001"]]]
>> Origin = (-8563840.575678950175643,6466755.550653258338571)
>> Pixel Size = (1420.390210742724321,-1420.394765779645695)
>> Metadata:
>>     TIFFTAG_XRESOLUTION=900
>>     TIFFTAG_YRESOLUTION=900
>>     TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
>>     AREA_OR_POINT=Area
>> Image Structure Metadata:
>>     INTERLEAVE=PIXEL
>> Corner Coordinates:
>> Upper Left  (-8563840.576, 6466755.551) ( 52d56'33.71"W,  8d
>> 9'27.23"S)
>> Lower Left  (-8563840.576,-6450314.449) (126d59'13.87"W,
>> 8d12'36.90"S)
>> Upper Right ( 8787646.239, 6466755.551) ( 53d39'3.45"E,  7d12'35.07"S)
>> Lower Right ( 8787646.239,-6450314.449) (126d16'45.99"E,
>> 7d15'38.97"S)
>> Center      (  111902.832,    8220.551) ( 85d47'54.65"E, 88d58'2.41"S)
>> Band 1 Block=256x256 Type=Byte, ColorInterp=Red
>>     Overviews: 6108x4547, 3054x2274, 1527x1137, 764x569
>>     Metadata:
>>       LAYER_TYPE=athematic
>> Band 2 Block=256x256 Type=Byte, ColorInterp=Green
>>     Overviews: 6108x4547, 3054x2274, 1527x1137, 764x569
>>     Metadata:
>>       LAYER_TYPE=athematic
>> Band 3 Block=256x256 Type=Byte, ColorInterp=Blue
>>     Overviews: 6108x4547, 3054x2274, 1527x1137, 764x569
>>     Metadata:
>>       LAYER_TYPE=athematic
>>
>> If I understood well the output of gdalinfo, the projection
>> seems to be
>> EPSG:4326.
>> Now I want to re-project this to EPSG:3031.
>> I tried with the following MAP file :
>>
>> MAP
>>       NAME "antarctic"
>>       STATUS ON
>>       SIZE 600 400
>>       EXTENT -8563840.576 -6450314.449 8787646.239 6466755.551
>>       IMAGECOLOR 255 255 255
>>
>>       PROJECTION
>>           "init=epsg:3031"
>>       END
>>
>>       OUTPUTFORMAT
>>           NAME png
>>           DRIVER "GD/PNG"
>>           MIMETYPE "image/png"
>>           IMAGEMODE RGBA
>>           EXTENSION "png"
>>       END
>>
>>       LAYER
>>           NAME "ocean"
>>           TYPE RASTER
>>           STATUS DEFAULT
>>           DATA antarctica_sthn_ocean.tiff
>>           PROJECTION
>>               "init=epsg:4326"
>>           END
>>       END
>> END
>>
>> ... but all what I get is a gray 600x400 PNG image ...
>>
>> Any idea what could be the problem ?
>>
>> Thanks,
>> Julien
>>


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