Overriding GeoTIFF projection with world file

[Frank Warmerdam]

Rahkonen Jukka wrote:
> Hi,
>  
> I must use two different projections (epsg:2393 and 3067) which both 
> have a common centre meridian 27°E.  One is transverse Mercator with 
> scale factor 1, another UTM with scale factor 0.996.  Now I can use the 
> same images, without any physical or on-the-fly reprojection simply by 
> creating two sets of world files with adjusted origos and pixel 
> sizes. Actually in my case this leads also to better accuracy because 
> another system has some local distortions which I can compensate by 
> sliding the origo to correct place with world file.
> But I have a problem: vast majority of my images are in GeoTIFF format 
> having internally defined coordinate system epsg:3067.  I wonder if 
> there is some trick to override this projection by world files.  
> Something like a hidden switch TRUST_WORLDFILE=YES which I could use in 
> the mapfile.  Does such a switch exist?

Jukka,

I'm afraid there is no such option.

Alternate approaches include:

1) reprocess the tiff so it has no internal geo information.  For example,
    with gdal_translate -co PROFILE=BASELINE

2) Create a VRT wrapper for the TIFF in which you can modify the geotransform
    and then use that VRT proxy in place of the TIFF.

3) well, I'm sure there are other methods.

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