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Getting ECW and MrSID support working in QGIS dev OSGeo4W install

Note:  This post is about getting ecw and mrsid support working in the trunk (qgis-dev) version of QGIS which is installed with the OSGeo4W installer.  Non-dev versions seem to work fine following this method:

Getting ECW and MrSID support into QGIS can be a real pain in the butt when you first try; but once you know how it’s easy.

If you try to open a ecw file in QGIS you will get this nice little error message:

What?  I thought QGIS supported ECW files!

Turns out it does, but the team are not able to ship the required libs with the program due to licensing restrictions by ERDAS.   Luckily adding support is not “too” hard.

  1. First head over to
  2. Click Download Now for the ERDAS ECW/JP2 SDK Desktop Read-Only, Version 4.1 libs,
  3. Fill out a bit of registration details and click though all the pages (this is the most painful process I have ever had to go though to get some libs for a program, ERDAS should be ashamed that it is such an effort.)
  4. Once you have download ECWJP2SDKSetup_RO_20100920.exe; install it.
  5. Copy all the files from C:\Program Files\ERDAS\ERDAS ECW JPEG2000 Read SDK\bin\vc90\win32 into the bin folder of your OSGeo4W install (default is C:\OSGeo4W\bin)
    You can open the OSgeo4W shell and run: copy “C:\Program Files\ERDAS\ERDAS ECW JPEG2000 Read SDK\bin\vc90\win32\*.dll” %OSGEO4W_ROOT%\bin to do the same thing.
  6. Launch osgeo4w-setup.exe, the installer that you used to install qgis-dev,  and select  gdal-ecw, gdal17-ecw and gdal-mrsid, gdal17-sid under the libs section. Let it install the needed libs and any dependencies.
  7. Open %OSGEO4W_ROOT%\bin and search for qgis-dev.bat; open it with a text editor and add the following line:
    set GDAL_DRIVER_PATH=”%OSGEO4W_ROOT%”\bin\gdalplugins\1.8
    I always insert it just after  SET OSGEO4W_ROOT=
  8. Launch qgis-dev.bat
  9. Open a ecw

ECW file opened in QGIS

I have tested this on a couple of machines now but as always

with no guarantee that it will work on yours :)  (Although it should)

Filed under: Open Source, qgis Tagged: ecw, gis, mapping, mrsid, Open Source, qgis, Quantum GIS, raster

Batch convert a directory of tiffs to ecw

Today I wanted to batch convert a directory of .tiff images to .ecw (MrSid wavelet compressed). Our server has 8 cores so it would be nice to use them all right?

Here is the quick & dirty way I do this kind of job in parallel.

mkdir ecw
for FILE in *.tif
  BASENAME=$(basename $FILE .tif)
  echo "Processing: ${BASENAME}.tif"
  if [ -f $OUTFILE ] #skip if exists
    echo "Skipping: $OUTFILE"
    /usr/local/bin/gdal_translate -of ECW -co LARGE_OK=YES $FILE $OUTFILE

The script is extremely simple and is set up so that you can run it multiple times without problems because if looks to see if the output file already exists before trying to write it. If it does exist, it skips straight on to the next image.

To run 8 parallel processes I simply do this at the command prompt (I did mine in a screen session):

./toecw &
./toecw &
./toecw &
./toecw &
./toecw &
./toecw &
./toecw &
./toecw &

Afterwards you can fire up top and watch 'em go!

top - 18:21:04 up  6:41,  4 users,  load average: 10.29, 9.83, 6.69
Tasks: 216 total,   1 running, 215 sleeping,   0 stopped,   0 zombie
Cpu0  : 56.5%us, 22.5%sy,  0.0%ni, 15.7%id,  4.9%wa,  0.0%hi,  0.3%si,  0.0%st
Cpu1  : 53.3%us, 31.6%sy,  0.0%ni,  8.9%id,  6.2%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu2  : 50.7%us, 37.5%sy,  0.0%ni,  4.9%id,  6.6%wa,  0.0%hi,  0.3%si,  0.0%st
Cpu3  : 46.6%us, 38.4%sy,  0.0%ni,  4.9%id,  9.8%wa,  0.0%hi,  0.3%si,  0.0%st
Cpu4  : 44.0%us, 29.8%sy,  0.0%ni,  8.7%id, 17.2%wa,  0.0%hi,  0.3%si,  0.0%st
Cpu5  : 30.7%us, 57.4%sy,  0.0%ni,  1.7%id,  9.6%wa,  0.0%hi,  0.7%si,  0.0%st
Cpu6  : 58.3%us, 23.8%sy,  0.0%ni,  9.4%id,  8.5%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu7  : 46.1%us, 38.6%sy,  0.0%ni, 10.1%id,  4.6%wa,  0.0%hi,  0.7%si,  0.0%st
Mem:  16227956k total, 16144508k used,    83448k free,  1739140k buffers
Swap: 62492832k total,        0k used, 62492832k free, 13383020k cached

12717 timlinux  18  -2  197m  85m 5384 D  104  0.5   0:55.49 gdal_translate
12536 timlinux  18  -2  171m  77m 5384 S  102  0.5   1:08.95 gdal_translate
12705 timlinux  18  -2  195m  65m 5384 D  100  0.4   0:52.58 gdal_translate
12737 timlinux  18  -2  194m  64m 5384 D   97  0.4   0:40.78 gdal_translate
12549 timlinux  18  -2  195m 103m 5384 S   95  0.7   1:12.68 gdal_translate
12751 timlinux  18  -2  165m  66m 5384 S   88  0.4   0:37.46 gdal_translate
12561 timlinux  18  -2  166m  67m 5384 D   69  0.4   1:03.91 gdal_translate
12528 timlinux  18  -2  164m  65m 5384 S   16  0.4   0:18.24 gdal_translate

One thing to note - I ran this with the data sitting on a storage array - if your data all lives on a single drive you may have serious IO issues doing the above....

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