[gdal-dev] gdal_merge.py stitched output image intermittent projection info loss

[Frank Warmerdam]

Dori wrote:
> Hi,
> I have used gdal_merge.py to stitch geotiff images created with a 3rd 
> party software for a couple of years now.
> These programs were moved to new hosts a while ago and from there on, 
> although the stitching works the output image seems to loose the 
> projection information when they are created at certain times of day but 
> not at some other times.
> When the projection info is lost, the image cannot be viewed in the 3rd 
> party software used to create the images been stitched, making it 
> useless. However, all images can be displayed with ImageMagick or openEV.
> 
> Is there any command I could use to make sure the projection information 
> is stored in the output image at all times? 

Dori,

You can use gdalinfo to check the projection information.

> I think my intermittent problem might be cause by some memory shortage 
> on the new hosts at certain times of the day .  The input images are not 
> very big ~4 Mb each and there is 16 of them. The output images are not 
> that huge either:~22Mb
> If this is true then, there is not much I could do to resolve my 
> immediate problems.
> I am no expert so, I may be missing the real cause of the problem.
> 
> What makes it hard to guess what it is is the fact that there are no 
> errors logged as the program work all the time.

I *suspect* you are running into problems that have now been fixed
in GDAL and libtiff.  Are you using GDAL 1.6.0?  Are you using the latest
libtiff distributed with GDAL or a recent libtiff 4 beta?  If not, I
would suggest you upgrade.

Best regards,
-- 
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