[Gdal-dev] saving GeoTiff

[Frank Warmerdam]

Ayman Kamal wrote:
> I want to be able to convert a "bmp" file to a
> "GeoTiff" file.
> 
> I used gdal_translate to do this, but the resulting
> file didn't of course contain georeferencing data.
> 
> Now:
> 1. Is it possible (if I find the goereferencing data)
> to give them to GDAL SDK so that GDAL can generate a
> GeoTiff file with georeferencing data embeded inside?
> 
> if (1.)
> {
>    2. What data do I need to supply to GDAL to    
>    accomplish this?
>    
>    3. What functions to use in GDAL to save such data 
>    in thre resulting GeoTiff file?
> }
> else
> {
>    4. Can you help me in any means to accomoplish
> this?
> }

Ayman,

You need to call GDALSetGeoTransform() with the appropriate affine geotransform.
Please ensure you are using a fairly recent GDAL (like a CVS snapshot not less
than 3 weeks old as there were some bugs in GeoTIFF update-in-place in 1.1.8).

The following is a fairly minimal example.  If you want to write the coordinate
system also use the GDALSetProjection() method.

#include "gdal.h"

int main()

{
     GDALDatasetH hDS;
     double       adfGeoTransform[6];

     GDALAllRegister();

     hDS = GDALOpen( "work.tif", GA_Update );

     adfGeoTransform[0] = 1000;  /* top left x */
     adfGeoTransform[1] = 2.0;   /* horizontal pixel size */
     adfGeoTransform[2] = 0.0;
     adfGeoTransform[3] = 6120;  /* top left y */
     adfGeoTransform[4] = 0.0;
     adfGeoTransform[5] = -2.0;  /* vertical pixel size */

     GDALSetGeoTransform( hDS, adfGeoTransform );

     GDALClose( hDS );
}

Best regards,

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