[Gdal-dev] No reprojection occurs

[Frank Warmerdam]

On 5/4/05, Ilya Serebrianik <predator2448 at hotmail.com> wrote:
> INPUT: 
>   
> PROJCS["NAD83 / UTM zone
> 17N",GEOGCS["NAD83",DATUM["North_American_Datum_1983",SPHEROID["GRS
> 1980",6378137,298.2572221010002,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6269"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4269"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-81],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AUTHORITY["EPSG","26917"]]
>   
> OUTPUT: 
>   
> GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS
> 84",6378137,298.2572235630016,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4326"]]
>   
>          I used the above in the Compose Dataset function in OpenEV and
> using the geotransform reprojection I converted the original geotiff from
> NAD83 to WGS84, the result came out to be what I expected from the
> beginning, which is a slightly rotated image and slightly squished from top
> to bottom. I do not know how OpenEV uses GDAL to make the correct
> transformation, but in my case it does not work. If someone can help me I
> would really appreciate it. Thank you very much ahead. I pasted the code
> below. I could make screenshots if that would help. 

Ilya, 

In the above case with OpenEV you are actually going from 
UTM 11N NAD83 to Lat/Long WGS84, so it is a very significant 
conversion.  The conversion being going from UTM to lat/long.  

Internally NAD83 and WGS84 are considered identical by the
GDAL and PROJ.4 code, so that reprojection should never have
an effect.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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