[mapserver-users] reprojection

[Rahkonen Jukka]

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-

> -----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
>