[Qgis-user] Raster data formats

Wed May 20 07:10:14 PDT 2009

Hi all,
did anyone seen the mail, (Fwd: RE: [Fwd: ECW licence]) passed on the
qgis-dev list, sent by Paolo and the following answer by Tim?

Is this finally a real step forward to have gdal compiled and packaged
with ecw (and mrsid) support?

-- Giovanni --

On Sat, 2009-05-16 at 12:38 +0200, Agustin Lobo wrote:
> The problem is, as I understand it, that Juan is not using Windows but 
> Linux. And while
> ECW&Mrsid support is simply added by
> the user to the current binary distribution of qgis
> for windows (i.e., see 
> http://sites.google.com/site/eospansite/qsig-for-windows )
> getting the same support for qgis installed from binaries for linux is
> simply impossible.
> You must go through the much more cumbersome
> process of
> (1) Compiling gdal with support for ecw and Mrsid
> (2) Compiling qgis with that particular gdal
> 
> Certainly, not a 5 minutes task (in particular for users who just don't even
> know what compiling means...)
> 
> So, effectively, regarding qgis, linux users are in disadvantage. Or, in 
> other
> words, for a regular user of qgis, using windows is better. An astonishing
> contradiction for gnu software.
> 
> The roots of the problem are in gdal, it's true. But the branches are in 
> qgis
> and, after having exchanged messages in the gdal list
> http://n2.nabble.com/Tickets-2385-and-2683-(ECW-and-MrSID-plugins)-tt2767156.html#none
> I'm convinced that the problem will not be solved unless the communities 
> behind
> programs using gdal get involved.
> 
> Agus
> 
> Tim Sutton wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Hi
> >
> > Alex Mandel wrote:
> >   
> >> Juan Pedro Pérez Alcántara wrote:
> >>     
> >>> Hello,
> >>>
> >>> perhaps this is a silly one, but I'm quite frustrated with conversions
> >>> from popular raster formats in the Windows/ArcGIS world to the
> >>> Linux/QGIS one. For example, ECW and MrSID are most popular. I think
> >>> JPEG2000 should be a good candidate for a raster format in QGIS. As far
> >>> as I know, it is fast (piramidized by nature, so to say),
> >>> georreferenced, and they work flawlessly and smoothly (my experience, at
> >>> least) in QGIS. Perhaps all of you, much experienced than me for sure,
> >>> think that JPEG2000 is not the way and that GeoTIFF or whatever should
> >>> do the job. If it is so, I'll stick obviously to that option instead.
> >>>
> >>> I have been messing around with quite a bunch of libraries to deal with
> >>> the conversion. First, there is GDAL, with which I'm able to transform
> >>> ECW to almost any GeoTIFF or JPEG that works with QGIS very well, and
> >>> with JPEG compression, not so far in size from the ECW source. But then
> >>> I tried to use ImageMagick and/or Jasper to convert to JPEG2000, and
> >>> here is where I get stuck. I stripped off in gdal_translate the GeoTIFF
> >>> tags with BASELINE, but to no avail in ImageMagick, it says always (with
> >>> TIFF, JPEG, etc.) that it cannot write the image. Same with JASPER: I
> >>> tried to convert from a gdal_translated jpeg, but without result. What
> >>> is that I'm missing? Do you have a proven workflow to do this job? 
> >>>
> >>> And with MrSID... not experimented by now, but I tremble only thinking
> >>> in that :)
> >>>
> >>> Perhaps I'm too obsessed with size (file sizes, I mean!!! :) ), and I'm
> >>> messing around too much with that subject, when GeoTIFF is providing
> >>> good results with a slight size increase. Given the size of hard drives
> >>> today (and that I'm not in the massive storage business in the GIS
> >>> scene), I think is a fair trade-off for an easy and straightforward
> >>> conversion workflow. I'd like very much to hear your opinions about
> >>> this.
> >>>
> >>> Thanks in advance, this is my first post. QGIS is great and thanks to it
> >>> and we have almost left behind the so-called industrial standard in GIS.
> >>> Congratulations for the great job.
> >>>
> >>> Greetings from Spain,
> >>>
> >>> Juan Pedro Pérez Alcántara
> >>>
> >>>       
> >> I think I'm a little confused, if you have GDAL compiled with ECW and
> >> MrSID format these should open in QGIS. Note the most recent version of
> >> the windows QGIS standalone is shipping with MrSID support.
> >>
> >> FYI, the MrSID license is more open, and LizardTech is a sponsor of OSGEO.
> >>
> >> Alex
> >>     
> >
> > Also note that if you want ECW support in windows builds of QGIS 1.0.2
> > or 1.1.0, you can simply download the ECW dlls from Erdas (by getting
> > the SDK) and place the dlls into the Quantum GIS/bin directory. We could
> > not include them in the installer by default for licensing reasons, but
> > by adding those dlls its pretty easy to get it working.
> >
> > Also note that in my testing the JASPER jp2 raster loading via GDAL is
> > quite slow (frustratingly slow really) on the only real performant way
> > to use a wavelet compressed raster at this stage is to use the Kakadu,
> > Mr Sid or ECW drivers (all of which are proprietary software).
> >
> > Lastly it is probably more appropriate to use gdal_translate to convert
> > between raster formats than imagemagick, since gdal's conversions are
> > 'spatially aware' and will retain all georeferencing etc. data in the image.
> >
> > Regards
> >
> >
> > - --
> >
> > Tim Sutton - QGIS Project Steering Committee Member (Release  Manager)
> > ==============================================
> > Please do not email me off-list with technical
> > support questions. Using the lists will gain
> > more exposure for your issues and the knowledge
> > surrounding your issue will be shared with all.
> >
> > Visit http://linfiniti.com to find out about:
> >  * QGIS programming and support services
> >  * Mapserver and PostGIS based hosting plans
> >  * FOSS Consulting Services
> > Skype: timlinux
> > Irc: timlinux on #qgis at freenode.net
> > ==============================================
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