[Gdal-dev] VRT file creation from multiple geotiff files

[Rahkonen Jukka]

Frank Warmerdam wrote:
>list67 <at> netscape.net wrote:
>> Hi.  I have many geotiff files.  I think that they are all the same projection 
>> and resolution.  They are all either adjacent or overlap each other.  I'd
>> like for GDAL to treat them as a single dataset.  My current method for
>> accomplishing this is to run gdal_merge and create a single .img file, and 
>>then pass that filename to GDAL.
 
>> Is there a more immediate method?  For example, could all the geotiffs be 
>> referenced by a single .vrt file?

>Yes, this can be done, but the VRT mechanism isn't necessarily going
>to scale up well to alot of individual files.  10's would be ok.
>100's might not be ok.

>> If so, is there a program that can generate that .vrt file?

>No, unfortunately not.

For me using VRT has worked just fine with some 120 JPEG 2000 files, 
10000 by 10000 pixels each. VRT can by made by a modifield gdal_merge.py 
script as Dardo D. Kleiner informed. Here is another link posted by 
Norman Vine to Mapserver user list:

">> A modified gdal_merge script was once posted to gdal_dev
>> mailing list, that creates GDAL/VRT file from a file list in seconds.
>> Here is a slightly modified version of that
> http://www.vso.cape.com/~nhv/files/gdal/gdal_vrtmerge.py
> # modified output of geotransform to retain same numerical
> # precision as the gdal 'C' utilities
> # Norman Vine  nhv at cape.com  03-Oct-2005 6:23:45 am
Note this has been added to the $GDAL_CVS / pymod / samples directory

Cheers

Norman"