Frank Warmerdam wrote:
> 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
Yes, I know that this would work, but I hate this option anyway. I have 20000
image files and removing geoinformation from them would take at least 3 minutes
per image. Even one minute per image would mean 333 hours. And I would like to
keep the internal geoinformation inside the image file because usually it is
extremely useful.
> 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.
How about trying to motivate some clever developer to create the option I
mentioned... Point 1) might give me possibilities for making an investment. I
fear this feature is not too much of general interest.
-Jukka-
