[gdal-dev] Generic way to extract Projection & CRS Information from raster imagery

[mattia]

Hi Folks,

I was just wondering if there is a generic way to extract CRS/Projection
information from a generic raster image for which there exists geo
information..

What would be nice would be to use the output from gdalinfo to extract a
Proj4 CRS string which defines the coordinate system of the image under
investigation..

For example, I have a SPOT image with the following gdalinfo output:

Driver: GTiff/GeoTIFF
Files: IMAGERY.TIF
Size is 24000, 24000
Coordinate System is `'
GCP Projection = GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,
298.2572235629972
,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0],UNIT["degree",
0.0174532925199433],AUTHORITY["EPSG","4326"]]
GCP[  0]: Id=1, Info=
          (1,1) -> (12.2141588220865,42.2864439118571,0)
GCP[  1]: Id=2, Info=
          (24000,1) -> (12.9457778570306,42.1574501849122,0)
GCP[  2]: Id=3, Info=
          (24000,24000) -> (12.773880153851,41.6326270994087,0)
GCP[  3]: Id=4, Info=
          (1,24000) -> (12.0481891024801,41.7611321956389,0)
Metadata:
  AREA_OR_POINT=Point
  TIFFTAG_IMAGEDESCRIPTION=PAN
  TIFFTAG_DATETIME=2002:10:24 10:52:26
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0,24000.0)
Upper Right (24000.0,    0.0)
Lower Right (24000.0,24000.0)
Center      (12000.0,12000.0)
Band 1 Block=24000x128 Type=Byte, ColorInterp=Gray



What would the Proj4 string be in this case?

How to generalize to any type of imagery and using gdalinfo's output??

Thanks in advance


-- 
Mattia
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