[Gdal-dev] Confusion with gdalwarp

R. Piepul rob at dataflowdesign.com
Thu Jun 19 10:49:51 EDT 2003

>>>>> "Richard" == Richard Greenwood <Rich at greenwoodmap.com> writes:

Hi Richard,
Thanks for responding. I'm taking Frank's suggestion and rebuilding
using the latest software in CVS but did try your suggestions.

    >> I seem to have a misunderstanding about the use of gdalwarp and
    >> am hoping that someone can tell me what is wrong.  I am trying
    >> to prepare a GeoTiff image for use in mapserver.
    >> I'm using gdalwarp to project a GeoTiff raster image.  The
    >> coordinates of the input file are in lat long.  After
    >> processing the file with gdalwarp, I used gdalinfo to examine
    >> the output file.  It appears that the coordinate system
    >> information is no longer there. Also, the corner coordinates in
    >> the output file are in pixels.
    >> I was expecting gdalinfo to display information about the
    >> projected coordinate system.  Also, I expected the corner
    >> coordinates to be displayed in projected units (meters).  Is
    >> this the normal behavior for gdalwarp?  I'm concerned that I
    >> may have a configuration or build issue.
    >> Thanks for your help, Rob

    Richard> Do you have your PROJ_LIB environment variable to point
    Richard> to the directory holding the "epsg" file.

The epsg file is found and I have used that notation to set the
projection successfully when using proj

    Richard> Alternatively you can define it something like: -t_srs
    Richard> "+proj=utm +ellps=GRS80 +zone=12 +north +datum=NAD83
    Richard> +units=m" (not your zone!). And if it was me, I'd also
    Richard> try defining you s_srs, too.

Tried it, same results. I should have added in my original post that
the resulting image file displays correctly so I think that the
projection works correctly.
Thanks for your help,

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