[Qgis-user] QGIS and ECW and MrSid formats

[Tom Elwertowski]

William Kyngesburye wrote:
> On Oct 31, 2008, at 7:17 AM, Martin Dobias wrote:
> 
>>> While I'm not a developer, the with my (very) little understanding of how
>>> QGIS and gdal interact, I don't think this is possible with a plugin.
>>
>> For all work with raster data (except WMS) we use GDAL.
>> So, support for ecw/mrsid must be compiled against gdal.
> 
>> - for mac I have no idea
>>
> For my framework-based Mac Qgis, GDAL is separate from Qgis.  My GDAL 
> framework has separately downloadable plugins for the ECW and MrSID 
> drivers, to avoid incompatible license problems.
> 
> Qgis has no problems reading ECW and MrSID when the GDAL plugins are 
> installed, without rebuilding or repackaging Qgis.
> 
> Tom's all-in-one includes the GDAL library, so ECW and MrSID would have 
> to be included in the Qgis package.

William builds and distributes Mac ECW and MrSID plugins to GDAL. I 
build a Mac GRASS plugin for GDAL. It ought to be possible to do the 
same thing for other platforms.

GDAL provides a configure script to add GRASS support as a plugin rather 
then built-in. There are no configure scripts for ECW and MrSID but it 
should be possible to copy and modify the GRASS plugin build script. 
William must have either done this or written his own build routine 
since he has created working Mac GDAL plugins.

Ubuntu also distributes GRASS as a GDAL plugin rather then built-in. 
QGIS doesn't need to directly distribute ECW and MrSID. Special builds 
of GDAL also shouldn't be needed. Someone who knows automake and GDAL 
just needs to replicate the existing GDAL/GRASS plugin build process and 
then build ECW and MrSID plugins for whatever distribution they use.

Tom