Re: [gdal-dev] How do I select 3 of 5 bands for output?

[Lucena, Ivan]

Hi Steve,

No, VRT files are not Geotiff, see [1], and they should not take more than a bunch of Kbytes. The problem is that in *our* gdal_translate command line *we* forgot "-of vrt" and the default format is Geotiff.

   system("gdaltranslate -OF VRT $infile -b 1 -b 2 -b 3 tmp.vrt");

Good luck,

Ivan

[1]: http://www.gdal.org/gdal_vrttut.html

>  -------Original Message-------
>  From: Stephen Woodbridge <woodbri at swoodbridge.com>
>  Subject: Re: [gdal-dev] How do I select 3 of 5 bands for output?
>  Sent: Nov 08 '08 03:36
>  
>  Stephen Woodbridge wrote:
>  > Lucena, Ivan wrote:
>  >> Hi Steve,
>  >>
>  >>>  I have a script that was processing MrSID files and need to convert it
>  >>>  to support jp2 files also. It seems pretty straight forward except the
>  >>>  jp2 files have bands R,G,B,IR and I need to chop these into GeoTif
>  >>> tiles
>  >>>  with only R,G,B bands.
>  >>>  
>  >>>  The script was iterating over the src image and chopping it into tiles
>  >>>  using the following command:
>  >>>  
>  >>>  system("gdalwarp -srcnodata 0 -dstnodata 0 -s_srs +init=epsg:$epsg
>  >>>  -t_srs EPSG:4326 -te $xm $ym $xx $yx -rb -wm 250 --config
>  >>>  GDAL_ONE_BIG_READ ON -co "TILED=YES" $infile $work/$outd/$outf\n");
>  >>>  
>  >>>  1) How does this behave with R,G,B,IR as input and how can I get R,G,B
>  >>>  only into the GeoTif?
>  >>
>  >> I would add one call to gdal_translate with "-b 1 -b 2 -b 3" first to
>  >> build a VRT and then call gdalwarp from the VRT.
>  >>
>  >> {
>  >>   system("gdaltranslate $infile -b 1 -b 2 -b 3 tmp.vrt");
>  >>   system("gdalwarp -srcnodata 0 -dstnodata 0 -s_srs +init=epsg:$epsg
>  >> -t_srs EPSG:4326 -te $xm $ym $xx $yx -rb -
>  >> wm 250 --config GDAL_ONE_BIG_READ ON -co "TILED=YES" tmp.vrt
>  >> $work/$outd/$outf\n");
>  >> }
>  >> system("gdalmanage delete tmp.vrt");
>  >
>  > OK, this might work, but it is incredibly slow. Then again probably
>  > doing much of anything with these images will be slow because they are
>  > HUGE. So looking for ways to speed this up. It looks like the .vrt file
>  > is really a GeoTif would it help later if the .vrt was made with -co
>  > "TILED=YES", can you do this with a .vrt file. I think the uncompressed
>  > 3 band geoTif will be in the ballpark of 10GB, is this being made as a
>  > BigTiff? or will I run into problems when I hit the 2GB limit?
>  >
>  > Anyway to get this to go faster? CPU is at 101%, 78MB of memory is being
>  > used, I have LOTS more if I can get gdal to use it.
>  
>  OK, it took 2 hr 10 min to run:
>  
>  GDAL_SKIP=JPEG2000 gdal_translate
>  /var/data/raw_data/minnesota/ortho_1-1_1m_j_mn161_2008_1.jp2  -b 1 -b 2
>  -b 3 tmp.vrt
>  
>  and the output file is 5.0 GB. And on top of this I still need to
>  gdalwarp this VRT file a bunch of times to chop it into smaller tiles. I
>  have hundreds of files to process. Any thoughts on how to speed this up?
>  
>  -Steve
>  
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