[Gdal-dev] gdalwarp -rc -tr 250 250 ortho_*.tif overview.tif error

[Frank Warmerdam]

John Mitchell wrote:
> Frank,
> 
> If I can't use the *-tr* /xres yres then how do I set the resolution to 
> be 250 meters?/
> Below is the results from gdalinfo:
> Driver: GTiff/GeoTIFF
> Size is 18308, 16757
> Coordinate System is:
> 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"]]
> Origin = (-90.086129408167338,29.957590557694168)
> Pixel Size = (0.000001458940448 ,-0.000001458940448)

John,

OK, so my guess was right.  The problem is that -tr needs to be
expressed in the output coordinate system which is currently geographic
decimal degrees.  If you want to stick with that then you will need
to work out an approximate decimal degree size that corresponds with
a 250 m pixel size.

According to my computations 250m x 250m is roughly 0.00225 degrees by
0.00225 degrees.  So try "-tr 0.00225 0.00225" instead.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org