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I am looking for a method for convert orthophotomap (.adf files) to ERDAS .ecw file.

Have you got any ideas ?

Or maybe you have got any other idea how i can reduce a size of orthophotomap .adf files? Now i have got 16 GB file I want to compress it to something like 3-4GB- is it even possible?

I read that .ecw is highly compressed for raster formats...

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You will need a paid Licence of the ERDAS SDK as the free (gratis) SDK is read-only. As an alternative try the Geotiff format with JPG compression.

For example, using the following two commands (but you have GUIs in QGIS, for example) to convert ECWs to TIFFs you get rasters that are more or less 30% bigger than then ECWs but look the same and are also as fast as ECWs

gdal_translate -co "TILED=YES" -co "INTERLEAVE=PIXEL" -co \
"EPSG:output_epsg_projection_code" $ecw $tif

gdaladdo --config COMPRESS_OVERVIEW JPEG --config \
$tif 2 4 8 16
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I already have tried to convert this .adf files to Geotiff (in ArcGIS) but i get an error that the file exceed maximum size (it can not be larger than 4 GB). – com Jan 3 '12 at 11:45
You need a copy of GDAL with BIGTiff support enabled, see I'm pretty sure that GDAL provided with FWtools, OSGeo4w, QGIS, etc. should support BIGTiff creation out of the box. – Giovanni Manghi Jan 3 '12 at 12:06
What about JPEG2000? I thought it was comparable to ECW. – dchaboya Jan 3 '12 at 13:30

You can use GDAL to convert ADF to ECW. The ECW driver is not provided by default in GDAL, you need to compile GDAL and link to the external ECW SDK libraries provided by ERDAS.

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You may find my blog post helpful on demystifying ECW

The example actually uses a raw input dataset of around 16gb that matches your original request

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