Andreas Neumann escribió: > Hello, > > I would like to discuss the loading of big images in QGIS: I have an > aerial image with 56000 x 44000 pixel. I tried three different approaches. > I wanted to just use one single file instead of tiles. I used gdal to > prepare the images. > > Here are my results: > > * ECW: > - compresses fine > - 500mb limit doesn't seem to apply if I use the -co "LARGE_OK=YES" > - loads fine and fast with UMN > - loads very, very long in QGIS: >4 minutes > - once loaded zooming and panning is very quick > On what O.S. are you running qgis? What qgis version? It takes over 10 minutes for me on debian using ecw files between 1-2 GB (tested with different revisions after 0.9.1 release). Zooming, panning or toggle vector layers edition takes the same time, not quick as you report. See bug #778 (https://trac.osgeo.org/qgis/ticket/778) for more info. > * Erdas imagine (HFA) > - spill files don't support compression, spill files have to be used if > the filesize is bigger than 2GB > - loads very fast in QGIS, less than a second > - once loaded zooming and panning is slower compared with ecw > > * bigtiff: couldn't get this to work > > So, as a result I would, from a technical point of view, like to go with > ecw, if the initial, very long loading time could be fixed in QGIS. > > So, here are my questions: > - will I run into licensing problem with ecw?, esp. if my filesize is > bigger than 500mb? > - can the long loading times of the ecw files be fixed in qgis? > - are there other better alternatives besides ecw/erdas imagine/bigtiff? > > Thank you for discussing this issue. > > Andreas > >
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