[gdal-dev] need help with gdalwarp

[Frank Warmerdam]

Wendell Turner wrote:
> Hi,
> 
> I'm new to gdal an have a question about warping an image 
> that I would like help with.
> 
> I have a GeoTIFF image of a Lambert Conformal Conic
> projection of a map.  I would like to convert it to Mercator
> (so the longiude lines are parallel, and the latitude lines
> are straight).  Does gdalwarp do this?  What are the
> parameters for the projections?  Do I need to tell it the
> source and target spatial reference set?  What other options
> should I send to gdalwarp?

Wendell,

Yes, gdalwarp is the appropriate tool.

Does GDAL recognise the coordinate system of the source image?  Try
a "gdalinfo" on it, and see if there is a coordinate system description.

If so, it might be sufficient to do something like:

   gdalwarp src.tif -t_srs '+proj=merc +datum=WGS84' dst.tif

You might find some of the following helpful to understand coordinate systems
in GDAL/OGR a bit.

   http://www.gdal.org/ogr/osr_tutorial.html

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